Swift 基本语法04-"switch"和"for"

override func viewDidLoad() {
    super.viewDidLoad()
    
    demo(num: "10")
}

func demo(num: String) {
    
    switch num {
    case "10":
        print("优")  // 输出结果:优
    default:
        print("一般")
    }
}

switch (num) {
    case 10:
    {
        NSLog(@"优");
    }
        break;
        
    default:
        break;
}

switch num {
case "10":
    print("优")
default:
    print("一般")
}

override func viewDidLoad() {
    super.viewDidLoad()
    
    demo(num: "9")
}

func demo(num: String) {
    
    switch num {
    case "10", "9":
        print("优")  // 输出结果:优
    default:
        print("一般")
    }
}

switch num {
case "10", "9":
    print("优")
/**
 * 1.如果只写(case "8":)会出现红色错误提示:'case' label in a 'switch' should have at least one executable statement
 * 2.根据提示点击修复,会自行添加'break'
 */
case "8": break
default:
    print("一般")
}

// C-style for statement has been removed in Swift 3
// '++' is unavailable: it has been removed in Swift 3
for var i = 0; i < 10; i++ {
    
}

num = i++  等价代码
temp = i
num = temp
i = temp + 1

num = ++i 等价代码
i = i + 1
num = i

// 变量'i'在[0,5)进行循环
// 注意:(0..<5)之间不能乱插入空格,不然会报错
for i in 0..<5 {
    print(i)    // 输出:0,1,2,3,4
}

print("======")

// 变量'i'在[0,5]进行循环
for i in 0...5 {
    print(i)    // 输出:0,1,2,3,4,5
}

// CountableRange<Int>
let r1 = 0..<5
print(r1)   // 输出:0..<5

// CountableClosedRange<Int>
let r2 = 0...5
print(r2)   // 输出:0...5

// 反向输出 reversed()
for i in (0..<10).reversed() {
    print(i)    // 输出:9,8,7,6,5,4,3,2,1,0
}