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再探Swift基础，
前端之家小编觉得挺不错的，现在分享给大家，也给大家做个参考。
基础
tuples
// Tuples
var address = (number: 142,street: "Evergreen Terrace") //起名
print(address.number)
print(address.street)
address.0 = 167
print(address.0) //顺序
print(address.1)
let (house,street) = address //赋值
print(house)
print(street)
strings
// Strings
var hello = "Hello"
hello = hello + " World"
print(hello)
// String interpolation
print("I live at \(house),\(street)") //替换字符串的内容
let str = "I live at \(house + 10),\(street.uppercaseString)";print(str) //一行多句使用分号
numeric
// Numeric types and conversion
var thousands = 1_000 //千元的分隔符（1,000）
var radius = 4
let pi = 3.14159
var area = Double(radius) * Double(radius) * pi //类型转换问题
for循环
// For loops and ranges
let greeting = "Swift by Tutorials Rocks!"
var range = 1...5 //range是一种类型
for i in range {
print("\(i) - \(greeting)")
}
while循环
// While loops
var i = 0
while i < 5 {
print("\(i) - \(greeting)")
i++
}
if条件
// If statements
for i in 1...5 {
if i == 5 {
print(greeting.uppercaseString)
} else {
print(greeting)
}
}
switch
var direction = "up"
switch direction { //类型问题
case "down":
print("Going Down!")
case "up":
print("Going Up!")
default:
print("Going Nowhere")
}
var score = 570
var prefix: String
switch score {
case 1..<10: //类型问题
print("novice")
case 10..<100:
print("proficient")
case 100..<1000:
print("rock-star")
default:
print("awesome")
}
optional
var str: String!
println(str)
if let unwrappedStr = str { //解包的方式
println("Unwrapped! \(unwrappedStr.uppercaseString)")
} else {
println("Was nil")
}
if str != nil { //解包前的防御式
str = str.lowercaseString
println(str)
}
var maybeString: String? = "Hello Swift by Tutorials!"
let uppercase = maybeString?.uppercaseString
array
var array: [Int] = [1,2,3,4,5]
println(array[2])
array.append(6)
array.extend(7...10)
println(array)
// Challenge solution:
array.removeAtIndex(8)
array.removeAtIndex(6)
array.removeAtIndex(4)
array.removeAtIndex(2)
array.removeAtIndex(0)
println(array)
// Challenge solution: 添加任意类型元素的数组
var anyArray: [AnyObject] = []
anyArray.append(1)
anyArray.append("1")
println(anyArray)
dictionary
var dictionary: [Int:String] = [1: "Dog",2: "Cat"]
println(dictionary[1])
dictionary[3] = "Mouse"
dictionary[3] = nil //相当于删除3
println(dictionary)
// Challenge solution:
dictionary.updateValue("Elephant",forKey: 2) //更改
println(dictionary)
println(dictionary[1])
if let value = dictionary[1] { //从字典取出的为optional类型 拆包
println("Value is \(value)")
}
set
var setA: Set = [1,3]
setA.insert(1)
println(setA)
setA.remove(1)
println(setA)
var setB: Set = [2,6]
println(setA.intersect(setB)) //交集
// Challenge solution:
let divisibleBy3: Set = [3,6,9]
let divisibleBy2: Set = [2,8]
let union = divisibleBy2.union(divisibleBy3) //并集
