1   for (int i = 0; i < 10; i++) {
2  
3   }     

 1 // 区间遍历 0..<10 0...9
 2 for i in 0..<10 {
 3     print(i)
 4 }
 5 
 6 for i in 0...9 {
 7     print(i)
 8 }
 9  
10 // 如果一个标识符不需要使用, 那么可以通过 _ 来代替
11 for _ in 0..<10 {
12     print("hello world")
13 }

 int a = 20
 while (a) {
 }

1 var i = 10
2 while i > 0 {
3     print(i)
4     i -= 1
5 }

1 // 区别: 不再使用do while --> repeat while
2 var m = 0
3 repeat {
4     print(m)
5     m += 1
6 } while m < 10

let str = "hello swift"

var strM = "hello world"
strM = "hello china" 

let length = str.characters.count

for c in str.characters {
    print(c)
}
 

let str1 = "Hello"
let str2 = "World"
let str3 = str1 + str2

let name = "lgp"
let age = 18
let height = 1.98
let infoStr = "my name is \(name), age is \(age), height is \(height)"

let min = 3
let second = 4
let timeStr = String(format: "%02d:%02d", arguments: [min, second]) 

1 // 1.方式一: 将String类型转成NSString类型, 再进行截取
2 // (urlString as NSString) --> NSString
3 let header = (urlString as NSString).substringToIndex(3)
4 let footer = (urlString as NSString).substringFromIndex(10)
5 let range = NSMakeRange(4, 5)
6 let middle = (urlString as NSString).substringWithRange(range)

1 // 2.方式二: Swift原生方式进行截取
2 let headerIndex = urlString.startIndex.advancedBy(3)
3 let header1 = urlString.substringToIndex(headerIndex)
4 
5 let footerIndex = urlString.endIndex.advancedBy(-3)
6 let footer1 = urlString.substringFromIndex(footerIndex)
7  
8 let range1 = headerIndex.advancedBy(1)..<footerIndex.advancedBy(-1)
9 let middle1 = urlString.substringWithRange(range1)

     let array = ["why", "yz"]    

  //基本写法   
  var arrayM = Array<String>()
  //单写法
  var arrayM = [String]()

arrayM.append("ljp")    

let removeItem = arrayM.removeAtIndex(1)  返回值为删除的元素
arrayM.removeAll()

arrayM[0] = "why"

let item = arrayM[0]

1 for i in 0..<array.count {
2     print(array[i])
3 }

for name in array {
    print(name)
} 

1 for (index, name) in array.enumerate() {
2     print(index)
3     print(name)
4 }

1 let array1 = ["why", "yz"]
2 let array2 = ["lmj", "lnj"]
3 let resultArray = array1 + array2

let dict = ["name" : "why", "age" : 18, "height" : 1.88]

var dictM = Dictionary<String, NSObject>()

var dictM = [String : NSObject]() // 常见

dictM.updateValue("why", forKey: "name")    

1 dictM.removeValueForKey("age") 

1 //如果原有没有对应的key/value, 那么就添加键值对
2 // 如果原有已经有对应的key/value, 那么直接修改
3 dictM.updateValue("1.77", forKey: "height")
4 dictM["name"] = "why"

1 let item = dictM["name"]

1 for key in dict.keys {
2     print(key)
3 }       

1 for value in dict.values {
2     print(value)
3 }

1 for (key, value) in dict {
2     print(key)
3     print(value)
4 }

1 let dict1 = ["name" : "why", "age" : 18]
2 var dict2 = ["height" : 1.88, "phoneNum" : "+86 110"]
3 
4 for (key, value) in dict1 {
5     dict2[key] = value
6 }
7  

1 let infoTuple = ("why", 18, 1.88, "+86 110")
2 // 使用元组描述一个人的信息
3 ("1001", "张三", 30, 90)
4 // 给元素加上元素名称,之后可以通过元素名称访问元素
5 (id:"1001", name:"张三", english_score:30, chinese_score:90)