By default, Swift assigns the raw values starting at zero and incrementing by one each time, but you can change this behavior by explicitly specifying values. In the example above, Ace is explicitly given a raw value of 1, and the rest of the raw values are assigned in order. You can also use strings or floating-point numbers as the raw type of. To help people who want to write Mac apps in Swift, I’ve written this tutorial that walks you through creating a simple Mac app in Swift. The app generates and displays a random number when you click a button. Create the Project. The first step is to open Xcode and create a project. Choose File New Project to create a new Xcode project. Download Step by Step Tutorials for Xcode 8 and IOS 10 for macOS 10.9 or later and enjoy it on your Mac. Step by step guide for the Mac OSX and IOS development software, Xcode 8. Xcode uses Objective-C and Swift programming languages. Our course covers all the subjects that every beginner needs. How to integrate Alamofire with macOS app to perform network calls; How to create a drag and drop mechanic; Some Swift 3.2 syntax; What will we build? I’m sure you are excited to know what good stuff we will be building! In this tutorial, we will be working on Mac’s main application layer, Cocoa. This layer is responsible for the appearance. I liked this class. Very Nice Graphic & Slot Machine App. (I hope building my First iOS App, and download in App Store. I'll follow your instructions. This class is designed for Create beautiful, dynamic apps faster than ever before. Development with the Swift programming language in xcode. Keep up the good work and wish you all the.
- Macos App Sandbox
- Swift Macos Example
- Swift Macos App Tutorial Mac
- Swift Macos App Tutorial Android Studio
- Swift Macos App Tutorial Windows 10
- Macos App Download
- Essential Macos Apps
- A Swift Tour
Tradition suggests that the first program in a new language should print the words “Hello, world!” on the screen. In Swift, this can be done in a single line:
If you have written code in C or Objective-C, this syntax looks familiar to you—in Swift, this line of code is a complete program. You don’t need to import a separate library for functionality like input/output or string handling. Code written at global scope is used as the entry point for the program, so you don’t need a
main()
function. You also don’t need to write semicolons at the end of every statement.This tour gives you enough information to start writing code in Swift by showing you how to accomplish a variety of programming tasks. Don’t worry if you don’t understand something—everything introduced in this tour is explained in detail in the rest of this book.
![Swift Swift](/uploads/1/3/4/1/134148497/686859777.jpg)
Note
For the best experience, open this chapter as a playground in Xcode.Playgrounds allow you to edit the code listings and see the result immediately.
Simple Values¶
Use
let
to make a constant and var
to make a variable. The value of a constant doesn’t need to be known at compile time, but you must assign it a value exactly once. This means you can use constants to name a value that you determine once but use in many places.- varmyVariable = 42
- myVariable = 50
- letmyConstant = 42
A constant or variable must have the same type as the value you want to assign to it. However, you don’t always have to write the type explicitly. Providing a value when you create a constant or variable lets the compiler infer its type. In the example above, the compiler infers that
myVariable
is an integer because its initial value is an integer.If the initial value doesn’t provide enough information (or if there is no initial value), specify the type by writing it after the variable, separated by a colon.
- letimplicitInteger = 70
- letimplicitDouble = 70.0
- letexplicitDouble: Double = 70
Audio oscilloscope app mac. Experiment
Create a constant with an explicit type of
Float
and a value of 4
.Values are never implicitly converted to another type. If you need to convert a value to a different type, explicitly make an instance of the desired type.
- letlabel = 'The width is '
- letwidth = 94
- letwidthLabel = label + String(width)
Experiment
Try removing the conversion to
String
from the last line. What error do you get?There’s an even simpler way to include values in strings: Write the value in parentheses, and write a backslash (
) before the parentheses. For example:- letapples = 3
- letoranges = 5
- letappleSummary = 'I have (apples) apples.'
- letfruitSummary = 'I have (apples + oranges) pieces of fruit.'
Experiment
Use
()
to include a floating-point calculation in a string and to include someone’s name in a greeting.Use three double quotation marks (
''
) for strings that take up multiple lines. Indentation at the start of each quoted line is removed, as long as it matches the indentation of the closing quotation marks. For example:- letquotation = ''
- I said 'I have (apples) apples.'
- And then I said 'I have (apples + oranges) pieces of fruit.'
- ''
Create arrays and dictionaries using brackets (
[]
), and access their elements by writing the index or key in brackets. A comma is allowed after the last element.- varshoppingList = ['catfish', 'water', 'tulips']
- shoppingList[1] = 'bottle of water'
- varoccupations = [
- 'Malcolm': 'Captain',
- 'Kaylee': 'Mechanic',
- ]
- occupations['Jayne'] = 'Public Relations'
Arrays automatically grow as you add elements.
- shoppingList.append('blue paint')
- print(shoppingList)
To create an empty array or dictionary, use the initializer syntax.
- letemptyArray = [String]()
- letemptyDictionary = [String: Float]()
If type information can be inferred, you can write an empty array as
[]
and an empty dictionary as [:]
—for example, when you set a new value for a variable or pass an argument to a function.Control Flow¶
Use
if
and switch
to make conditionals, and use for
-in
, while
, and repeat
-while
to make loops. Parentheses around the condition or loop variable are optional. Braces around the body are required.- letindividualScores = [75, 43, 103, 87, 12]
- varteamScore = 0
- forscoreinindividualScores {
- ifscore > 50 {
- teamScore += 3
- } else {
- teamScore += 1
- }
- }
- print(teamScore)
- // Prints '11'
In an
if
statement, the conditional must be a Boolean expression—this means that code such as ifscore{..}
is an error, not an implicit comparison to zero.You can use
if
and let
together to work with values that might be missing. These values are represented as optionals. An optional value either contains a value or contains nil
to indicate that a value is missing. Write a question mark (?
) after the type of a value to mark the value as optional.- varoptionalString: String? = 'Hello'
- print(optionalStringnil)
- // Prints 'false'
- varoptionalName: String? = 'John Appleseed'
- vargreeting = 'Hello!'
- ifletname = optionalName {
- greeting = 'Hello, (name)'
- }
Experiment
Change
optionalName
to nil
. What greeting do you get? Add an else
clause that sets a different greeting if optionalName
is nil
.If the optional value is
nil
, the conditional is false
and the code in braces is skipped. Otherwise, the optional value is unwrapped and assigned to the constant after let
, which makes the unwrapped value available inside the block of code.Another way to handle optional values is to provide a default value using the
??
operator. If the optional value is missing, the default value is used instead.- letnickname: String? = nil
- letfullName: String = 'John Appleseed'
- letinformalGreeting = 'Hi (nickname ?? fullName)'
Switches support any kind of data and a wide variety of comparison operations—they aren’t limited to integers and tests for equality.
- letvegetable = 'red pepper'
- switchvegetable {
- case'celery':
- print('Add some raisins and make ants on a log.')
- case'cucumber', 'watercress':
- print('That would make a good tea sandwich.')
- caseletxwherex.hasSuffix('pepper'):
- print('Is it a spicy (x)?')
- default:
- print('Everything tastes good in soup.')
- }
- // Prints 'Is it a spicy red pepper?'
Experiment
Try removing the default case. What error do you get?
Notice how
let
can be used in a pattern to assign the value that matched the pattern to a constant.After executing the code inside the switch case that matched, the program exits from the switch statement. Execution doesn’t continue to the next case, so there is no need to explicitly break out of the switch at the end of each case’s code.
You use
for
-in
to iterate over items in a dictionary by providing a pair of names to use for each key-value pair. Dictionaries are an unordered collection, so their keys and values are iterated over in an arbitrary order.- letinterestingNumbers = [
- 'Prime': [2, 3, 5, 7, 11, 13],
- 'Fibonacci': [1, 1, 2, 3, 5, 8],
- 'Square': [1, 4, 9, 16, 25],
- ]
- varlargest = 0
- for (kind, numbers) ininterestingNumbers {
- fornumberinnumbers {
- ifnumber > largest {
- largest = number
- }
- }
- }
- print(largest)
- // Prints '25'
Experiment
Add another variable to keep track of which kind of number was the largest, as well as what that largest number was.
Use
while
to repeat a block of code until a condition changes. The condition of a loop can be at the end instead, ensuring that the loop is run at least once.- varn = 2
- whilen < 100 {
- n *= 2
- }
- print(n)
- // Prints '128'
- varm = 2
- repeat {
- m *= 2
- } whilem < 100
- print(m)
- // Prints '128'
You can keep an index in a loop by using
.<
to make a range of indexes.- vartotal = 0
- foriin0.<4 {
- total += i
- }
- print(total)
- // Prints '6'
Use
.<
to make a range that omits its upper value, and use ..
to make a range that includes both values.Functions and Closures¶
Use
func
to declare a function. Call a function by following its name with a list of arguments in parentheses. Use ->
to separate the parameter names and types from the function’s return type.- funcgreet(person: String, day: String) -> String {
- return'Hello (person), today is (day).'
- }
- greet(person: 'Bob', day: 'Tuesday')
Experiment
Remove the
day
parameter. Add a parameter to include today’s lunch special in the greeting.By default, functions use their parameter names as labels for their arguments. Write a custom argument label before the parameter name, or write
_
to use no argument label.- funcgreet(_person: String, onday: String) -> String {
- return'Hello (person), today is (day).'
- }
- greet('John', on: 'Wednesday')
Use a tuple to make a compound value—for example, to return multiple values from a function. The elements of a tuple can be referred to either by name or by number.
- funccalculateStatistics(scores: [Int]) -> (min: Int, max: Int, sum: Int) {
- varmin = scores[0]
- varmax = scores[0]
- varsum = 0
- forscoreinscores {
- ifscore > max {
- max = score
- } elseifscore < min {
- min = score
- }
- sum += score
- }
- return (min, max, sum)
- }
- letstatistics = calculateStatistics(scores: [5, 3, 100, 3, 9])
- print(statistics.sum)
- // Prints '120'
- print(statistics.2)
- // Prints '120'
Functions can be nested. Nested functions have access to variables that were declared in the outer function. You can use nested functions to organize the code in a function that is long or complex.
- funcreturnFifteen() -> Int {
- vary = 10
- funcadd() {
- y += 5
- }
- add()
- returny
- }
- returnFifteen()
Functions are a first-class type. This means that a function can return another function as its value.
- funcmakeIncrementer() -> ((Int) -> Int) {
- funcaddOne(number: Int) -> Int {
- return1 + number
- }
- returnaddOne
- }
- varincrement = makeIncrementer()
- increment(7)
A function can take another function as one of its arguments.
- funchasAnyMatches(list: [Int], condition: (Int) -> Bool) -> Bool {
- foriteminlist {
- ifcondition(item) {
- returntrue
- }
- }
- returnfalse
- }
- funclessThanTen(number: Int) -> Bool {
- returnnumber < 10
- }
- varnumbers = [20, 19, 7, 12]
- hasAnyMatches(list: numbers, condition: lessThanTen)
Functions are actually a special case of closures: blocks of code that can be called later. The code in a closure has access to things like variables and functions that were available in the scope where the closure was created, even if the closure is in a different scope when it is executed—you saw an example of this already with nested functions. You can write a closure without a name by surrounding code with braces (
{}
). Use in
to separate the arguments and return type from the body.- numbers.map({ (number: Int) -> Intin
- letresult = 3 * number
- returnresult
- })
Experiment
Rewrite the closure to return zero for all odd numbers.
You have several options for writing closures more concisely. When a closure’s type is already known, such as the callback for a delegate, you can omit the type of its parameters, its return type, or both. Single statement closures implicitly return the value of their only statement.
- letmappedNumbers = numbers.map({ numberin3 * number })
- print(mappedNumbers)
- // Prints '[60, 57, 21, 36]'
You can refer to parameters by number instead of by name—this approach is especially useful in very short closures. A closure passed as the last argument to a function can appear immediately after the parentheses. When a closure is the only argument to a function, you can omit the parentheses entirely.
- letsortedNumbers = numbers.sorted { $0 > $1 }
- print(sortedNumbers)
- // Prints '[20, 19, 12, 7]'
Objects and Classes¶
Use
class
followed by the class’s name to create a class. A property declaration in a class is written the same way as a constant or variable declaration, except that it is in the context of a class. Likewise, method and function declarations are written the same way.- classShape {
- varnumberOfSides = 0
- funcsimpleDescription() -> String {
- return'A shape with (numberOfSides) sides.'
- }
- }
Experiment
Add a constant property with
let
, and add another method that takes an argument.Create an instance of a class by putting parentheses after the class name. Use dot syntax to access the properties and methods of the instance.
- varshape = Shape()
- shape.numberOfSides = 7
- varshapeDescription = shape.simpleDescription()
This version of the
Shape
class is missing something important: an initializer to set up the class when an instance is created. Use init
to create one.- classNamedShape {
- varnumberOfSides: Int = 0
- varname: String
- init(name: String) {
- self.name = name
- }
- funcsimpleDescription() -> String {
- return'A shape with (numberOfSides) sides.'
- }
- }
Notice how
self
is used to distinguish the name
property from the name
argument to the initializer. The arguments to the initializer are passed like a function call when you create an instance of the class. Every property needs a value assigned—either in its declaration (as with numberOfSides
) or in the initializer (as with name
).Use
deinit
to create a deinitializer if you need to perform some cleanup before the object is deallocated.Subclasses include their superclass name after their class name, separated by a colon. There is no requirement for classes to subclass any standard root class, so you can include or omit a superclass as needed.
Methods on a subclass that override the superclass’s implementation are marked with
override
—overriding a method by accident, without override
, is detected by the compiler as an error. The compiler also detects methods with override
that don’t actually override any method in the superclass.- classSquare: NamedShape {
- varsideLength: Double
- init(sideLength: Double, name: String) {
- self.sideLength = sideLength
- super.init(name: name)
- numberOfSides = 4
- }
- funcarea() -> Double {
- returnsideLength * sideLength
- }
- overridefuncsimpleDescription() -> String {
- return'A square with sides of length (sideLength).'
- }
- }
- lettest = Square(sideLength: 5.2, name: 'my test square')
- test.area()
- test.simpleDescription()
Experiment
Make another subclass of
NamedShape
called Circle
that takes a radius and a name as arguments to its initializer. Implement an area()
and a simpleDescription()
method on the Circle
class.In addition to simple properties that are stored, properties can have a getter and a setter.
- classEquilateralTriangle: NamedShape {
- varsideLength: Double = 0.0
- init(sideLength: Double, name: String) {
- self.sideLength = sideLength
- super.init(name: name)
- numberOfSides = 3
- }
- varperimeter: Double {
- get {
- return3.0 * sideLength
- }
- set {
- sideLength = newValue / 3.0
- }
- }
- overridefuncsimpleDescription() -> String {
- return'An equilateral triangle with sides of length (sideLength).'
- }
- }
- vartriangle = EquilateralTriangle(sideLength: 3.1, name: 'a triangle')
- print(triangle.perimeter)
- // Prints '9.3'
- triangle.perimeter = 9.9
- print(triangle.sideLength)
- // Prints '3.3000000000000003'
In the setter for
perimeter
, the new value has the implicit name newValue
. You can provide an explicit name in parentheses after set
.Notice that the initializer for the
EquilateralTriangle
class has three different steps:- Setting the value of properties that the subclass declares.
- Calling the superclass’s initializer.
- Changing the value of properties defined by the superclass. Any additional setup work that uses methods, getters, or setters can also be done at this point.
If you don’t need to compute the property but still need to provide code that is run before and after setting a new value, use
willSet
and didSet
. The code you provide is run any time the value changes outside of an initializer. For example, the class below ensures that the side length of its triangle is always the same as the side length of its square.- classTriangleAndSquare {
- vartriangle: EquilateralTriangle {
- willSet {
- square.sideLength = newValue.sideLength
- }
- }
- varsquare: Square {
- willSet {
- triangle.sideLength = newValue.sideLength
- }
- }
- init(size: Double, name: String) {
- square = Square(sideLength: size, name: name)
- triangle = EquilateralTriangle(sideLength: size, name: name)
- }
- }
- vartriangleAndSquare = TriangleAndSquare(size: 10, name: 'another test shape')
- print(triangleAndSquare.square.sideLength)
- // Prints '10.0'
- print(triangleAndSquare.triangle.sideLength)
- // Prints '10.0'
- triangleAndSquare.square = Square(sideLength: 50, name: 'larger square')
- print(triangleAndSquare.triangle.sideLength)
- // Prints '50.0'
When working with optional values, you can write
?
before operations like methods, properties, and subscripting. If the value before the ?
is nil
, everything after the ?
is ignored and the value of the whole expression is nil
. Otherwise, the optional value is unwrapped, and everything after the ?
acts on the unwrapped value. In both cases, the value of the whole expression is an optional value.- letoptionalSquare: Square? = Square(sideLength: 2.5, name: 'optional square')
- letsideLength = optionalSquare?.sideLength
Enumerations and Structures¶
Use
enum
to create an enumeration. Like classes and all other named types, enumerations can have methods associated with them.- enumRank: Int {
- caseace = 1
- casetwo, three, four, five, six, seven, eight, nine, ten
- casejack, queen, king
- funcsimpleDescription() -> String {
- switchself {
- case .ace:
- return'ace'
- case .jack:
- return'jack'
- case .queen:
- return'queen'
- case .king:
- return'king'
- default:
- returnString(self.rawValue)
- }
- }
- }
- letace = Rank.ace
- letaceRawValue = ace.rawValue
Experiment
Write a function that compares two
Rank
values by comparing their raw values.By default, Swift assigns the raw values starting at zero and incrementing by one each time, but you can change this behavior by explicitly specifying values. In the example above,
Ace
is explicitly given a raw value of 1
, and the rest of the raw values are assigned in order. You can also use strings or floating-point numbers as the raw type of an enumeration. Use the rawValue
property to access the raw value of an enumeration case.Use the
init?(rawValue:)
initializer to make an instance of an enumeration from a raw value. It returns either the enumeration case matching the raw value or nil
if there is no matching Rank
.- ifletconvertedRank = Rank(rawValue: 3) {
- letthreeDescription = convertedRank.simpleDescription()
- }
The case values of an enumeration are actual values, not just another way of writing their raw values. In fact, in cases where there isn’t a meaningful raw value, you don’t have to provide one.
- enumSuit {
- casespades, hearts, diamonds, clubs
- funcsimpleDescription() -> String {
- switchself {
- case .spades:
- return'spades'
- case .hearts:
- return'hearts'
- case .diamonds:
- return'diamonds'
- case .clubs:
- return'clubs'
- }
- }
- }
- lethearts = Suit.hearts
- letheartsDescription = hearts.simpleDescription()
Experiment
Add a
color()
method to Suit
that returns “black” for spades and clubs, and returns “red” for hearts and diamonds.Notice the two ways that the
hearts
case of the enumeration is referred to above: When assigning a value to the hearts
constant, the enumeration case Suit.hearts
is referred to by its full name because the constant doesn’t have an explicit type specified. Inside the switch, the enumeration case is referred to by the abbreviated form .hearts
because the value of self
is already known to be a suit. You can use the abbreviated form anytime the value’s type is already known.If an enumeration has raw values, those values are determined as part of the declaration, which means every instance of a particular enumeration case always has the same raw value. Another choice for enumeration cases is to have values associated with the case—these values are determined when you make the instance, and they can be different for each instance of an enumeration case. You can think of the associated values as behaving like stored properties of the enumeration case instance. For example, consider the case of requesting the sunrise and sunset times from a server. The server either responds with the requested information, or it responds with a description of what went wrong.
- enumServerResponse {
- caseresult(String, String)
- casefailure(String)
- }
- letsuccess = ServerResponse.result('6:00 am', '8:09 pm')
- letfailure = ServerResponse.failure('Out of cheese.')
- switchsuccess {
- caselet .result(sunrise, sunset):
- print('Sunrise is at (sunrise) and sunset is at (sunset).')
- caselet .failure(message):
- print('Failure.. (message)')
- }
- // Prints 'Sunrise is at 6:00 am and sunset is at 8:09 pm.'
Experiment
Add a third case to
ServerResponse
and to the switch.Notice how the sunrise and sunset times are extracted from the
ServerResponse
value as part of matching the value against the switch cases.Use
struct
to create a structure. Structures support many of the same behaviors as classes, including methods and initializers. One of the most important differences between structures and classes is that structures are always copied when they are passed around in your code, but classes are passed by reference.- structCard {
- varrank: Rank
- varsuit: Suit
- funcsimpleDescription() -> String {
- return'The (rank.simpleDescription()) of (suit.simpleDescription())'
- }
- }
- letthreeOfSpades = Card(rank: .three, suit: .spades)
- letthreeOfSpadesDescription = threeOfSpades.simpleDescription()
Experiment
Write a function that returns an array containing a full deck of cards, with one card of each combination of rank and suit.
Protocols and Extensions¶
Use
protocol
to declare a protocol.- protocolExampleProtocol {
- varsimpleDescription: String { get }
- mutatingfuncadjust()
- }
Classes, enumerations, and structs can all adopt protocols.
- classSimpleClass: ExampleProtocol {
- varsimpleDescription: String = 'A very simple class.'
- varanotherProperty: Int = 69105
- funcadjust() {
- simpleDescription += ' Now 100% adjusted.'
- }
- }
- vara = SimpleClass()
- a.adjust()
- letaDescription = a.simpleDescription
- structSimpleStructure: ExampleProtocol {
- varsimpleDescription: String = 'A simple structure'
- mutatingfuncadjust() {
- simpleDescription += ' (adjusted)'
- }
- }
- varb = SimpleStructure()
- b.adjust()
- letbDescription = b.simpleDescription
Experiment
Add another requirement to
ExampleProtocol
. What changes do you need to make to SimpleClass
and SimpleStructure
so that they still conform to the protocol?Notice the use of the
mutating
keyword in the declaration of SimpleStructure
to mark a method that modifies the structure. The declaration of SimpleClass
doesn’t need any of its methods marked as mutating because methods on a class can always modify the class.Use
extension
to add functionality to an existing type, such as new methods and computed properties. You can use an extension to add protocol conformance to a type that is declared elsewhere, or even to a type that you imported from a library or framework.- extensionInt: ExampleProtocol {
- varsimpleDescription: String {
- return'The number (self)'
- }
- mutatingfuncadjust() {
- self += 42
- }
- }
- print(7.simpleDescription)
- // Prints 'The number 7'
Experiment
Write an extension for the
Double
type that adds an absoluteValue
property.You can use a protocol name just like any other named type—for example, to create a collection of objects that have different types but that all conform to a single protocol. When you work with values whose type is a protocol type, methods outside the protocol definition are not available.
- letprotocolValue: ExampleProtocol = a
- print(protocolValue.simpleDescription)
- // Prints 'A very simple class. Now 100% adjusted.'
- // print(protocolValue.anotherProperty) // Uncomment to see the error
Even though the variable
protocolValue
has a runtime type of SimpleClass
, the compiler treats it as the given type of ExampleProtocol
. This means that you can’t accidentally access methods or properties that the class implements in addition to its protocol conformance.Error Handling¶
You represent errors using any type that adopts the
Error
protocol.- enumPrinterError: Error {
- caseoutOfPaper
- casenoToner
- caseonFire
- }
Use
throw
to throw an error and throws
to mark a function that can throw an error. If you throw an error in a function, the function returns immediately and the code that called the function handles the error.- funcsend(job: Int, toPrinterprinterName: String) throws -> String {
- ifprinterName'Never Has Toner' {
- throwPrinterError.noToner
- }
- return'Job sent'
- }
There are several ways to handle errors. One way is to use
do
-catch
. Inside the do
block, you mark code that can throw an error by writing try
in front of it. Inside the catch
block, the error is automatically given the name error
unless you give it a different name.- do {
- letprinterResponse = trysend(job: 1040, toPrinter: 'Bi Sheng')
- print(printerResponse)
- } catch {
- print(error)
- }
- // Prints 'Job sent'
Experiment
Change the printer name to
'NeverHasToner'
, so that the send(job:toPrinter:)
function throws an error.You can provide multiple
catch
blocks that handle specific errors. You write a pattern after catch
just as you do after case
in a switch.- do {
- letprinterResponse = trysend(job: 1440, toPrinter: 'Gutenberg')
- print(printerResponse)
- } catchPrinterError.onFire {
- print('I'll just put this over here, with the rest of the fire.')
- } catchletprinterErrorasPrinterError {
- print('Printer error: (printerError).')
- } catch {
- print(error)
- }
- // Prints 'Job sent'
Experiment
Add code to throw an error inside the
do
block. What kind of error do you need to throw so that the error is handled by the first catch
block? What about the second and third blocks?Another way to handle errors is to use
try?
to convert the result to an optional. If the function throws an error, the specific error is discarded and the result is nil
. Otherwise, the result is an optional containing the value that the function returned.- letprinterSuccess = try? send(job: 1884, toPrinter: 'Mergenthaler')
- letprinterFailure = try? send(job: 1885, toPrinter: 'Never Has Toner')
Use
defer
to write a block of code that is executed after all other code in the function, just before the function returns. The code is executed regardless of whether the function throws an error. You can use defer
to write setup and cleanup code next to each other, even though they need to be executed at different times.- varfridgeIsOpen = false
- letfridgeContent = ['milk', 'eggs', 'leftovers']
- funcfridgeContains(_food: String) -> Bool {
- fridgeIsOpen = true
- defer {
- fridgeIsOpen = false
- }
- letresult = fridgeContent.contains(food)
- returnresult
- }
- fridgeContains('banana')
- print(fridgeIsOpen)
- // Prints 'false'
Generics¶
Write a name inside angle brackets to make a generic function or type.
- funcmakeArray<Item>(repeatingitem: Item, numberOfTimes: Int) -> [Item] {
- varresult = [Item]()
- for_in0.<numberOfTimes {
- result.append(item)
- }
- returnresult
- }
- makeArray(repeating: 'knock', numberOfTimes: 4)
You can make generic forms of functions and methods, as well as classes, enumerations, and structures.
- // Reimplement the Swift standard library's optional type
- enumOptionalValue<Wrapped> {
- casenone
- casesome(Wrapped)
- }
- varpossibleInteger: OptionalValue<Int> = .none
- possibleInteger = .some(100)
Use
where
right before the body to specify a list of requirements—for example, to require the type to implement a protocol, to require two types to be the same, or to require a class to have a particular superclass.- funcanyCommonElements<T: Sequence, U: Sequence>(_lhs: T, _rhs: U) -> Bool
- whereT.Element: Equatable, T.ElementU.Element
- {
- forlhsIteminlhs {
- forrhsIteminrhs {
- iflhsItemrhsItem {
- returntrue
- }
- }
- }
- returnfalse
- }
- anyCommonElements([1, 2, 3], [3])
Experiment
Modify the
anyCommonElements(_:_:)
function to make a function that returns an array of the elements that any two sequences have in common.Writing
<T:Equatable>
is the same as writing <T>..whereT:Equatable
.Learn serious code. In a seriously fun way.
Macos App Sandbox
Swift Playgrounds is a revolutionary app for iPad and Mac that makes learning Swift interactive and fun. It requires no coding knowledge, so it’s perfect for students just starting out. Solve puzzles to master the basics using Swift — a powerful programming language created by Apple and used by the pros to build today’s most popular apps. Then take on a series of challenges and step up to more advanced playgrounds designed by Apple and other leading developers.
Robots and drones await your commands.
Now you can make robots do incredible things with code you write yourself. Learn to program connected devices like the Sphero SPRK+, LEGO® MINDSTORMS® EV3, and drones by Parrot, and watch them come alive right before your eyes.
Now you can make robots do incredible things with code you write yourself. Learn to program connected devices like the Sphero SPRK+, LEGO® MINDSTORMS® EV3, and drones by Parrot, and watch them come alive right before your eyes.
Real Swift code.
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Learning to code with Swift Playgrounds is incredibly engaging. The app comes with a complete set of Apple-designed lessons. Play your way through the basics in “Fundamentals of Swift” using real code to guide a character through a 3D world. Then move on to more advanced concepts.
What you see is what you code: Create code on the left side of your screen and instantly see the results on the right — with just a tap.
Conquer levels, puzzles, and coding concepts.
Starting with the “Fundamentals of Swift” lesson, you’ll tackle goals using the same code professional developers use every day. As you move along, more advanced concepts come into play. You’ll continually build on what you’ve learned and create even more complex code.
Fundamentals of Swift.
You’ll start out by learning the important concepts you need to understand code. Quiver app mac crack.
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Master the basics,
then step up to more challenges.
In addition to the built-in library of lessons, Swift Playgrounds includes a collection of extra challenges — with new ones added over time. Go deeper on a topic you’ve already studied or try your hand at something new. You’re not just building fun creations, you’re building your skills, too.
A big world of playgrounds from a big community of developers.
Discover dozens of channels with fun new challenges created by leading developers and publishers. Subscribe to your favorites and you’ll receive their latest creations right in the app. Now there are no bounds to your playgrounds.
A new way to create code.
On the best device for learning.
Easily drag braces around code, wrap existing code in a loop, or choose from dozens of drag-and-drop snippets included in Swift Playgrounds — right from your iPad or Mac. Take full advantage of powerful Multi-Touch, multitasking, and split view capabilities on iPad. Also, enjoy the view from your Mac. The larger screen makes room for a new sidebar with a complete table of contents and quick access to other Swift files. Just tap, drag, or type text and numbers. Then interact with what you’ve created.
QuickType and coding keyboard.
Write an entire line of code with just a tap. With QuickType for code, the Shortcut Bar automatically and intelligently suggests commands as you go. When typing is the best option, iPad has an innovative keyboard designed for coding. Simply touch a key to access multiple characters, then drag to choose the one you want. Experience similar code suggestions on Mac, which comes with even more help to complete your code.
Snippets Library.
Quickly drag commonly used pieces of code from the Snippets Library to minimize typing.
Touch to edit.
Conveniently drag the boundaries of a statement around existing code.
![App App](/uploads/1/3/4/1/134148497/550385748.jpg)
Help is just a tap away.
If you come across a command that’s hard to understand, simply tap it and hold. A menu of options will appear. Choose the most relevant one and get the answer you need.
Jump-start your creativity with Starting Points.
Use what you’ve learned to create something brand new. With Starting Points, you can get a head start on more advanced coding, add multiple files to your playground at once, and use iPad features such as Multi-Touch interactions, accelerometer, and gyroscope. Personalize your project by adding graphics, audio, and more. Then easily share with friends, family, or the world. Students can also share code with classmates when teachers use Starting Points to create lessons.
Swift Macos Example
Explore your creations in full screen.
Swift Macos App Tutorial Mac
Immerse yourself by using the vivid Retina displays of iPad or Mac. Simply tap the center divider, then drag to view your code or live project on the full screen. You can also customize built-in games like Battleship and Brick Breaker, then immerse yourself by letting them take up the whole screen.
See your code crawl, roll, or fly through the sky.
Watch your code spring to life by programming real robots, musical instruments, and drones. The Accessories channel is filled with engaging playgrounds that let you configure and control popular educational toys like LEGO® MINDSTORMS® EV3. And that’s just the beginning.
Swift Macos App Tutorial Android Studio
Sphero playgrounds let you guide this spherical robot through tricky courses, accelerate over jumps, and change colors.
Dash playgrounds challenge you to make it sing, dance and respond to sensor inputs to react to their environment.
Swift Macos App Tutorial Windows 10
MeeBot playgrounds guide you through coding Jimu Robot Meebot’s six robotic servo motors to make him move in lifelike ways. Or even dance.
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Tello EDU playgrounds let you command multiple Tello drones to fly in a swarm, perform flips and other acrobatic movements, and push the limits of your creativity.
Essential Macos Apps
Explore robots, drones, and many other connected devices that support Swift Playgrounds.