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Conflicts:
	swift.html.markdown
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C. Bess
2015-11-09 17:55:53 -06:00
parent afc5ea1465 c460e1fafa
commit df0992d72c
222 changed files with 45346 additions and 4726 deletions
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@@ -3,6 +3,10 @@ language: swift
contributors:
- ["Grant Timmerman", "http://github.com/grant"]
- ["Christopher Bess", "http://github.com/cbess"]
- ["Joey Huang", "http://github.com/kamidox"]
- ["Anthony Nguyen", "http://github.com/anthonyn60"]
- ["Clayton Walker", "https://github.com/cwalk"]
- ["Fernando Valverde", "http://visualcosita.xyz"]
filename: learnswift.swift
---
@@ -10,7 +14,7 @@ Swift is a programming language for iOS and OS X development created by Apple. D
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/DevelopiOSAppsSwift/), which has a complete tutorial on Swift.
```swift
// import a module
@@ -22,10 +26,13 @@ import UIKit
// Xcode supports landmarks to annotate your code and lists them in the jump bar
// MARK: Section mark
// MARK: - Section mark with a separator line
// TODO: Do something soon
// FIXME: Fix this code
println("Hello, world")
// In Swift 2, println and print were combined into one print method. Print automatically appends a new line.
print("Hello, world") // println is now print
print("Hello, world", appendNewLine: false) // printing without appending a newline
// variables (var) value can change after being set
// constants (let) value can NOT be changed after being set
@@ -45,16 +52,17 @@ let piText = "Pi = \(π), Pi 2 = \(π * 2)" // String interpolation
// Build Specific values
// uses -D build configuration
#if false
println("Not printed")
print("Not printed")
let buildValue = 3
#else
let buildValue = 7
#endif
println("Build value: \(buildValue)") // Build value: 7
print("Build value: \(buildValue)") // Build value: 7
/*
Optionals are a Swift language feature that allows you to store a `Some` or
`None` value.
Optionals are a Swift language feature that either contains a value,
or contains nil (no value) to indicate that a value is missing.
A question mark (?) after the type marks the value as optional.
Because Swift requires every property to have a value, even nil must be
explicitly stored as an Optional value.
@@ -68,13 +76,19 @@ var someOptionalString2: Optional<String> = "optional"
if someOptionalString != nil {
// I am not nil
if someOptionalString!.hasPrefix("opt") {
println("has the prefix")
print("has the prefix")
}
let empty = someOptionalString?.isEmpty
}
someOptionalString = nil
/*
Trying to use ! to access a non-existent optional value triggers a runtime
error. Always make sure that an optional contains a non-nil value before
using ! to force-unwrap its value.
*/
// implicitly unwrapped optional
var unwrappedString: String! = "Value is expected."
// same as above, but ! is a postfix operator (more syntax candy)
@@ -89,13 +103,13 @@ if let someOptionalStringConstant = someOptionalString {
// Swift has support for storing a value of any type.
// AnyObject == id
// Unlike Objective-C `id`, AnyObject works with any value (Class, Int, struct, etc)
// Unlike Objective-C `id`, AnyObject works with any value (Class, Int, struct, etc.)
var anyObjectVar: AnyObject = 7
anyObjectVar = "Changed value to a string, not good practice, but possible."
/*
Comment here
/*
Nested comments are also supported
*/
@@ -116,6 +130,7 @@ shoppingList[1] = "bottle of water"
let emptyArray = [String]() // let == immutable
let emptyArray2 = Array<String>() // same as above
var emptyMutableArray = [String]() // var == mutable
var explicitEmptyMutableStringArray: [String] = [] // same as above
// Dictionary
@@ -127,6 +142,7 @@ occupations["Jayne"] = "Public Relations"
let emptyDictionary = [String: Float]() // let == immutable
let emptyDictionary2 = Dictionary<String, Float>() // same as above
var emptyMutableDictionary = [String: Float]() // var == mutable
var explicitEmptyMutableDictionary: [String: Float] = [:] // same as above
//
@@ -137,21 +153,21 @@ var emptyMutableDictionary = [String: Float]() // var == mutable
let myArray = [1, 1, 2, 3, 5]
for value in myArray {
if value == 1 {
println("One!")
print("One!")
} else {
println("Not one!")
print("Not one!")
}
}
// for loop (dictionary)
var dict = ["one": 1, "two": 2]
for (key, value) in dict {
println("\(key): \(value)")
print("\(key): \(value)")
}
// for loop (range)
for i in -1...shoppingList.count {
println(i)
print(i)
}
shoppingList[1...2] = ["steak", "peacons"]
// use ..< to exclude the last number
@@ -164,7 +180,7 @@ while i < 1000 {
// do-while loop
do {
println("hello")
print("hello")
} while 1 == 2
// Switch
@@ -221,8 +237,8 @@ let pricesTuple = getGasPrices()
let price = pricesTuple.2 // 3.79
// Ignore Tuple (or other) values by using _ (underscore)
let (_, price1, _) = pricesTuple // price1 == 3.69
println(price1 == pricesTuple.1) // true
println("Gas price: \(price)")
print(price1 == pricesTuple.1) // true
print("Gas price: \(price)")
// Named tuple params
func getGasPrices2() -> (lowestPrice: Double, highestPrice: Double, midPrice: Double) {
@@ -260,7 +276,7 @@ func swapTwoInts(inout a: Int, inout b: Int) {
var someIntA = 7
var someIntB = 3
swapTwoInts(&someIntA, &someIntB)
println(someIntB) // 7
print(someIntB) // 7
//
@@ -301,10 +317,10 @@ print(numbers) // [3, 6, 18]
// MARK: Structures
//
// Structures and classes have very similar capabilites
// Structures and classes have very similar capabilities
struct NamesTable {
let names = [String]()
// Custom subscript
subscript(index: Int) -> String {
return names[index]
@@ -314,7 +330,7 @@ struct NamesTable {
// Structures have an auto-generated (implicit) designated initializer
let namesTable = NamesTable(names: ["Me", "Them"])
let name = namesTable[1]
println("Name is \(name)") // Name is Them
print("Name is \(name)") // Name is Them
//
// MARK: Classes
@@ -335,7 +351,7 @@ public class Shape {
internal class Rect: Shape {
var sideLength: Int = 1
// Custom getter and setter property
private var perimeter: Int {
get {
@@ -346,16 +362,16 @@ internal class Rect: Shape {
sideLength = newValue / 4
}
}
// Computed properties must be declared as `var`, you know, cause they can change
// Computed properties must be declared as `var`, you know, cause' they can change
var smallestSideLength: Int {
return self.sideLength - 1
}
// Lazily load a property
// subShape remains nil (uninitialized) until getter called
lazy var subShape = Rect(sideLength: 4)
// If you don't need a custom getter and setter,
// but still want to run code before and after getting or setting
// a property, you can use `willSet` and `didSet`
@@ -365,19 +381,19 @@ internal class Rect: Shape {
print(someIdentifier)
}
}
init(sideLength: Int) {
self.sideLength = sideLength
// always super.init last when init custom properties
super.init()
}
func shrink() {
if sideLength > 0 {
--sideLength
}
}
override func getArea() -> Int {
return sideLength * sideLength
}
@@ -400,7 +416,36 @@ let aShape = mySquare as Shape
// compare instances, not the same as == which compares objects (equal to)
if mySquare === mySquare {
println("Yep, it's mySquare")
print("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)
print(myCircle?.getArea()) // Optional(3)
print(myCircle!.getArea()) // 3
var myEmptyCircle = Circle(radius: -1)
print(myEmptyCircle?.getArea()) // "nil"
if let circle = myEmptyCircle {
// will not execute since myEmptyCircle is nil
print("circle is not nil")
}
@@ -432,7 +477,29 @@ enum BookName: String {
case John = "John"
case Luke = "Luke"
}
println("Name: \(BookName.John.rawValue)")
print("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)
print(desk.description()) // "Desk with 80 cm"
var chair = Furniture.Chair("Foo", 40)
print(chair.description()) // "Chair of Foo with 40 cm"
//
@@ -457,10 +524,13 @@ protocol ShapeGenerator {
class MyShape: Rect {
var delegate: TransformShape?
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?()
@@ -482,21 +552,21 @@ extension Square: Printable {
}
}
println("Square: \(mySquare)")
print("Square: \(mySquare)")
// You can also extend built-in types
extension Int {
var customProperty: String {
return "This is \(self)"
}
func multiplyBy(num: Int) -> Int {
return num * self
}
}
println(7.customProperty) // "This is 7"
println(14.multiplyBy(2)) // 42
print(7.customProperty) // "This is 7"
print(14.multiplyBy(3)) // 42
// Generics: Similar to Java and C#. Use the `where` keyword to specify the
// requirements of the generics.
@@ -510,7 +580,7 @@ func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? {
return nil
}
let foundAtIndex = findIndex([1, 2, 3, 4], 3)
println(foundAtIndex == 2) // true
print(foundAtIndex == 2) // true
// Operators:
// Custom operators can start with the characters:
@@ -526,9 +596,23 @@ prefix func !!! (inout shape: Square) -> Square {
}
// current value
println(mySquare.sideLength) // 4
print(mySquare.sideLength) // 4
// change side length using custom !!! operator, increases size by 3
!!!mySquare
println(mySquare.sideLength) // 12
print(mySquare.sideLength) // 12
// Operators can also be generics
infix operator <-> {}
func <-><T: Equatable> (inout a: T, inout b: T) {
let c = a
a = b
b = c
}
var foo: Float = 10
var bar: Float = 20
foo <-> bar
print("foo is \(foo), bar is \(bar)") // "foo is 20.0, bar is 10.0"
```