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Diffstat (limited to 'swift.html.markdown')
| -rw-r--r-- | swift.html.markdown | 130 |
1 files changed, 105 insertions, 25 deletions
diff --git a/swift.html.markdown b/swift.html.markdown index 005e511c..ffc57e69 100644 --- a/swift.html.markdown +++ b/swift.html.markdown @@ -3,14 +3,15 @@ language: swift contributors: - ["Grant Timmerman", "http://github.com/grant"] - ["Christopher Bess", "http://github.com/cbess"] + - ["Joey Huang", "http://github.com/kamidox"] filename: learnswift.swift --- -Swift is a programming language for iOS and OS X development created by Apple. Designed to coexist with Objective-C and to be more resilient against erroneous code, Swift was introduced in 2014 at Apple's developer conference WWDC. It is built with the LLVM compiler included in Xcode 6 beta. +Swift is a programming language for iOS and OS X development created by Apple. Designed to coexist with Objective-C and to be more resilient against erroneous code, Swift was introduced in 2014 at Apple's developer conference WWDC. It is built with the LLVM compiler included in Xcode 6+. The official [Swift Programming Language](https://itunes.apple.com/us/book/swift-programming-language/id881256329) book from Apple is now available via iBooks. -See also Apple's [getting started guide](https://developer.apple.com/library/prerelease/ios/referencelibrary/GettingStarted/LandingPage/index.html), which has a complete tutorial on Swift. +See also Apple's [getting started guide](https://developer.apple.com/library/prerelease/ios/referencelibrary/GettingStarted/RoadMapiOS/index.html), which has a complete tutorial on Swift. ```swift // import a module @@ -23,7 +24,7 @@ import UIKit // Xcode supports landmarks to annotate your code and lists them in the jump bar // MARK: Section mark // TODO: Do something soon -// FIXME Fix this code +// FIXME: Fix this code println("Hello, world") @@ -55,8 +56,8 @@ println("Build value: \(buildValue)") // Build value: 7 /* Optionals are a Swift language feature that allows you to store a `Some` or `None` value. - - Because Swift requires every property to have a value, even nil must be + + Because Swift requires every property to have a value, even nil must be explicitly stored as an Optional value. Optional<T> is an enum. @@ -94,7 +95,8 @@ var anyObjectVar: AnyObject = 7 anyObjectVar = "Changed value to a string, not good practice, but possible." /* -Comment here + Comment here + /* Nested comments are also supported */ @@ -112,8 +114,9 @@ Comment here // Array var shoppingList = ["catfish", "water", "lemons"] shoppingList[1] = "bottle of water" -let emptyArray = [String]() // immutable -var emptyMutableArray = [String]() // mutable +let emptyArray = [String]() // let == immutable +let emptyArray2 = Array<String>() // same as above +var emptyMutableArray = [String]() // var == mutable // Dictionary @@ -122,8 +125,9 @@ var occupations = [ "kaylee": "Mechanic" ] occupations["Jayne"] = "Public Relations" -let emptyDictionary = [String: Float]() // immutable -var emptyMutableDictionary = [String: Float]() // mutable +let emptyDictionary = [String: Float]() // let == immutable +let emptyDictionary2 = Dictionary<String, Float>() // same as above +var emptyMutableDictionary = [String: Float]() // var == mutable // @@ -165,14 +169,16 @@ do { } while 1 == 2 // Switch +// Very powerful, think `if` statements with syntax candy +// They support String, object instances, and primitives (Int, Double, etc) let vegetable = "red pepper" switch vegetable { case "celery": let vegetableComment = "Add some raisins and make ants on a log." case "cucumber", "watercress": let vegetableComment = "That would make a good tea sandwich." -case let x where x.hasSuffix("pepper"): - let vegetableComment = "Is it a spicy \(x)?" +case let localScopeValue where localScopeValue.hasSuffix("pepper"): + let vegetableComment = "Is it a spicy \(localScopeValue)?" default: // required (in order to cover all possible input) let vegetableComment = "Everything tastes good in soup." } @@ -186,21 +192,28 @@ default: // required (in order to cover all possible input) // in functions and can be passed around // Function with Swift header docs (format as reStructedText) + /** -A greet operation + A greet operation -- A bullet in docs -- Another bullet in the docs + - A bullet in docs + - Another bullet in the docs -:param: name A name -:param: day A day -:returns: A string containing the name and day value. + :param: name A name + :param: day A day + :returns: A string containing the name and day value. */ func greet(name: String, day: String) -> String { return "Hello \(name), today is \(day)." } greet("Bob", "Tuesday") +// similar to above except for the function parameter behaviors +func greet2(#requiredName: String, externalParamName localParamName: String) -> String { + return "Hello \(requiredName), the day is \(localParamName)" +} +greet2(requiredName:"John", externalParamName: "Sunday") + // Function that returns multiple items in a tuple func getGasPrices() -> (Double, Double, Double) { return (3.59, 3.69, 3.79) @@ -281,7 +294,7 @@ print(numbers) // [3, 6, 18] // Structures and classes have very similar capabilites struct NamesTable { - let names: [String] + let names = [String]() // Custom subscript subscript(index: Int) -> String { @@ -291,8 +304,8 @@ struct NamesTable { // Structures have an auto-generated (implicit) designated initializer let namesTable = NamesTable(names: ["Me", "Them"]) -//let name = namesTable[2] -//println("Name is \(name)") // Name is Them +let name = namesTable[1] +println("Name is \(name)") // Name is Them // // MARK: Classes @@ -341,7 +354,7 @@ internal class Rect: Shape { init(sideLength: Int) { self.sideLength = sideLength - // always super.init last when init custom properties + // always super.init last when init custom properties super.init() } @@ -368,11 +381,43 @@ print(mySquare.getArea()) // 25 mySquare.shrink() print(mySquare.sideLength) // 4 +// cast instance +let aShape = mySquare as Shape + // compare instances, not the same as == which compares objects (equal to) if mySquare === mySquare { println("Yep, it's mySquare") } +// Optional init +class Circle: Shape { + var radius: Int + override func getArea() -> Int { + return 3 * radius * radius + } + + // Place a question mark postfix after `init` is an optional init + // which can return nil + init?(radius: Int) { + self.radius = radius + super.init() + + if radius <= 0 { + return nil + } + } +} + +var myCircle = Circle(radius: 1) +println(myCircle?.getArea()) // Optional(3) +println(myCircle!.getArea()) // 3 +var myEmptyCircle = Circle(radius: -1) +println(myEmptyCircle?.getArea()) // "nil" +if let circle = myEmptyCircle { + // will not execute since myEmptyCircle is nil + println("circle is not nil") +} + // // MARK: Enums @@ -393,6 +438,39 @@ enum Suit { } } +// Enum values allow short hand syntax, no need to type the enum type +// when the variable is explicitly declared +var suitValue: Suit = .Hearts + +// Non-Integer enums require direct raw value assignments +enum BookName: String { + case John = "John" + case Luke = "Luke" +} +println("Name: \(BookName.John.rawValue)") + +// Enum with associated Values +enum Furniture { + // Associate with Int + case Desk(height: Int) + // Associate with String and Int + case Chair(String, Int) + + func description() -> String { + switch self { + case .Desk(let height): + return "Desk with \(height) cm" + case .Chair(let brand, let height): + return "Chair of \(brand) with \(height) cm" + } + } +} + +var desk: Furniture = .Desk(height: 80) +println(desk.description()) // "Desk with 80 cm" +var chair = Furniture.Chair("Foo", 40) +println(chair.description()) // "Chair of Foo with 40 cm" + // // MARK: Protocols @@ -419,7 +497,10 @@ class MyShape: Rect { func grow() { sideLength += 2 - + + // Place a question mark after an optional property, method, or + // subscript to gracefully ignore a nil value and return nil + // instead of throwing a runtime error ("optional chaining"). if let allow = self.delegate?.canReshape?() { // test for delegate then for method self.delegate?.reshaped?() @@ -455,7 +536,7 @@ extension Int { } println(7.customProperty) // "This is 7" -println(14.multiplyBy(2)) // 42 +println(14.multiplyBy(3)) // 42 // Generics: Similar to Java and C#. Use the `where` keyword to specify the // requirements of the generics. @@ -490,5 +571,4 @@ println(mySquare.sideLength) // 4 // change side length using custom !!! operator, increases size by 3 !!!mySquare println(mySquare.sideLength) // 12 - ``` |