swift （循环与选择）

for in 正序

 for i in (0...10){
            
            print("循环循序：",i)
        }
        
 let arr = ["01","02","03","04","05"]
        
        for  str:String in arr {
            print("for循环：\(str)")
        }

for in 倒序

for i in (0...10).reversed() {
            
            print("循环倒序：",i)
        }
        

for in 获取元素与下标

//正序
let arr = ["字符串01","字符串02","字符串03","字符串04"];
        for (index,str) in arr.enumerated() {
            print("下标：\(index)----元素：\(str)")
        }

//倒序
for (index,str) in arr.enumerated().reversed() {
            print("下标：\(index)----元素：\(str)")
        }

while

var i = 0;
        while i < 10 {
            print("while循环\(i)")
            i = i + 1;
        }

if

 func ifTest(istrue:Bool) -> Void {
        
        if istrue == true {
            print("这是真")
        }
        else
        {
            print("这是假")
        }
        
    }  

switch

 func switchTest(index:NSInteger) -> Void {
        
        switch index {
        case 100:
            let newIndex = index + 1;
            print("新下标:",newIndex)
            break;
        case 200:
            let newIndex = index + 1;
            print("新下标2:",newIndex)
            break;
        default:
            break;
        }
    }