Swift 快速参考

本文是苹果Swift编程语言的备忘单和参考之南，以后会涵盖Swift的所有关键特性，包括Strings、Arrays、Dictionaries以及Flow Control。Swift是苹果在WWDC 2014上发布的适用于iOS和OS X平台应用的开发。（持续更新的内容，欢迎你来贴自己的备忘单）

Variables
<pre name="code" class="Swift">var myInt = 1
var myExplicitInt: Int = 1 // explicit type
var x = 1, y = 2, z = 3 // declare multiple integers
myExplicitInt = 2 // set to another integer value </pre>

Constants
<pre name="code" class="Swift">let myInt = 1
myInt = 2 // compile-time error! </pre>

Strings
<pre name="code" class="Swift">var myString = "a"
let myImmutableString = "c"
myString += "b" // ab
myString = myString + myImmutableString // abc
myImmutableString += "d" // compile-time error!

let count = 7
let message = "There are \(count) days in a week" </pre>

Logical Operators
<pre name="code" class="Swift">var happy = true
var sad = !happy // logical NOT, sad = false
var everyoneHappy = happy && sad // logical AND, everyoneHappy = false
var someoneHappy = happy || sad // logical OR, someoneHappy = true </pre>

Printing
<pre name="code" class="Swift">let name = "swift"
println("Hello")
println("My name is \(name)")
print("See you ")
print("later")
/*  Hello
    My name is swift
    See you later */ </pre>

Arrays
<pre name="code" class="Swift">var colors = ["red", "blue"]
var moreColors: String[] = ["orange", "purple"] // explicit type
colors.append("green") // [red, blue, green]
colors += "yellow" // [red, blue, green, yellow]
colors += moreColors // [red, blue, green, yellow, orange, purple]

var days = ["mon", "thu"]
var firstDay = days[0] // mon
days.insert("tue", atIndex: 1) // [mon, tue, thu]
days[2] = "wed" // [mon, tue, wed]
days.removeAtIndex(0) // [tue, wed]  </pre>

Dictionaries
<pre name="code" class="Swift">var days = ["mon": "monday", "tue": "tuseday"]
days["tue"] = "tuesday" // change the value for key "tue"
days["wed"] = "wednesday" // add a new key/value pair

var moreDays: Dictionary = ["thu": "thursday", "fri": "friday"]
moreDays["thu"] = nil // remove thu from the dictionary
moreDays.removeValueForKey("fri") // remove fri from the dictionary
</pre>

Conditionals
<pre name="code" class="Swift">//IF STATEMENT
let happy = true
if happy {
    println("We're Happy!")
} else {
    println("We're Sad'")
}
// We're Happy!

let speed = 28
if speed <= 0 {
    println("Stationary")
} else if speed <= 30 {
    println("Safe speed")
} else {
    println("Too fast!")
}
// Safe speed


//SWITCH STATEMENT
let n = 2
switch n {
case 1:
    println("It's 1!")
case 2...4:
    println("It's between 2 and 4!")
case 5, 6:
    println("It's 5 or 6")
default:
    println("Its another number!")
}
// It's between 2 and 4! </pre>

For Loops
<pre name="code" class="Swift">for var index = 1; index < 3; ++index {
    // loops with index taking values 1,2 
}
for index in 1..3 {
    // loops with index taking values 1,2
}
for index in 1...3 { 
    // loops with index taking values 1,2,3
}

let colors = ["red", "blue", "yellow"]
for color in colors {
    println("Color: \(color)")
}
// Color: red
// Color: blue
// Color: yellow 

let days = ["mon": "monday", "tue": "tuesday"]
for (shortDay, longDay) in days {
    println("\(shortDay) is short for \(longDay)")
}
// mon is short for monday
// tue is short for tuesday
</pre>


While Loops
<pre name="code" class="Swift">var count = 1
while count < 3 {
    println("count is \(count)")
    ++count
}
// count is 1
// count is 2

count = 1
while count < 1 {
    println("count is \(count)")
    ++count
}
//


count = 1
do {
    println("count is \(count)")
    ++count
} while count < 3
// count is 1
// count is 2

count = 1
do {
    println("count is \(count)")
    ++count
} while count < 1
// count is 1 </pre>



另附上raywenderlich上Ray Wenderlich的备忘单。