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-rw-r--r--swift.html.markdown119
1 files changed, 72 insertions, 47 deletions
diff --git a/swift.html.markdown b/swift.html.markdown
index ffc57e69..f451288d 100644
--- a/swift.html.markdown
+++ b/swift.html.markdown
@@ -3,7 +3,9 @@ language: swift
contributors:
- ["Grant Timmerman", "http://github.com/grant"]
- ["Christopher Bess", "http://github.com/cbess"]
- - ["Joey Huang", "http://github.com/kamidox"]
+ - ["Joey Huang", "http://github.com/kamidox"]
+ - ["Anthony Nguyen", "http://github.com/anthonyn60"]
+ - ["Clayton Walker", "https://github.com/cwalk"]
filename: learnswift.swift
---
@@ -11,7 +13,7 @@ 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/RoadMapiOS/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
@@ -26,7 +28,9 @@ import UIKit
// 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
@@ -46,16 +50,17 @@ 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.
@@ -69,13 +74,19 @@ 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)
@@ -90,13 +101,13 @@ 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
*/
@@ -138,21 +149,21 @@ 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
@@ -165,7 +176,7 @@ while i < 1000 {
// do-while loop
do {
- println("hello")
+ print("hello")
} while 1 == 2
// Switch
@@ -222,8 +233,8 @@ 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)")
// Variadic Args
func setup(numbers: Int...) {
@@ -251,7 +262,7 @@ func swapTwoInts(inout a: Int, inout b: Int) {
var someIntA = 7
var someIntB = 3
swapTwoInts(&someIntA, &someIntB)
-println(someIntB) // 7
+print(someIntB) // 7
//
@@ -292,10 +303,10 @@ 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]
@@ -305,7 +316,7 @@ 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
@@ -326,7 +337,7 @@ public class Shape {
internal class Rect: Shape {
var sideLength: Int = 1
-
+
// Custom getter and setter property
private var perimeter: Int {
get {
@@ -337,11 +348,11 @@ internal class Rect: Shape {
sideLength = newValue / 4
}
}
-
+
// 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`
@@ -351,19 +362,19 @@ 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
}
@@ -386,7 +397,7 @@ 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
@@ -395,13 +406,13 @@ class Circle: Shape {
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
}
@@ -409,13 +420,13 @@ class Circle: Shape {
}
var myCircle = Circle(radius: 1)
-println(myCircle?.getArea()) // Optional(3)
-println(myCircle!.getArea()) // 3
+print(myCircle?.getArea()) // Optional(3)
+print(myCircle!.getArea()) // 3
var myEmptyCircle = Circle(radius: -1)
-println(myEmptyCircle?.getArea()) // "nil"
+print(myEmptyCircle?.getArea()) // "nil"
if let circle = myEmptyCircle {
// will not execute since myEmptyCircle is nil
- println("circle is not nil")
+ print("circle is not nil")
}
@@ -447,7 +458,7 @@ 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 {
@@ -455,7 +466,7 @@ enum Furniture {
case Desk(height: Int)
// Associate with String and Int
case Chair(String, Int)
-
+
func description() -> String {
switch self {
case .Desk(let height):
@@ -467,9 +478,9 @@ enum Furniture {
}
var desk: Furniture = .Desk(height: 80)
-println(desk.description()) // "Desk with 80 cm"
+print(desk.description()) // "Desk with 80 cm"
var chair = Furniture.Chair("Foo", 40)
-println(chair.description()) // "Chair of Foo with 40 cm"
+print(chair.description()) // "Chair of Foo with 40 cm"
//
@@ -494,7 +505,7 @@ protocol ShapeGenerator {
class MyShape: Rect {
var delegate: TransformShape?
-
+
func grow() {
sideLength += 2
@@ -522,21 +533,21 @@ 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(3)) // 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.
@@ -550,7 +561,7 @@ 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:
@@ -566,9 +577,23 @@ 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"
```