基本控制

    var x = 0;
    repeat {
        x += 1
        print(x)
        if x > 3 {
            continue
        }
        if x > 4 {
            break
        }
    } while x < 5

    let p1 = (12, 13)
    if case (12, 13) = p1 {
        print("equal")
    }

    //value binding
    let p2 = "hello"
    switch p1 {
    case (0, 0):
        print("=====")

    case is String:
        print("is String")

    default:
        break
    }

    defer {
        print("Must do something")
    }

    let skills = ["JS", nil, "C", nil]
    for case let skill? in skills {
        print("Get \(skill) ")
    }

    let percentage = 0.5
    //Range 匹配
    if case 0...1 = percentage {
        print("In range")
    }

    let name = "FPP"
    let age = 34
    if case ("FPP", 34) = (name, age) {
        print("Match user")
    }

自定义约等

//样式匹配背后的准则
//Range ~= T 由系统实现了， 对应到了 if case 0...1 = percentage
//打印 ~  =  就是约等
func ~=<T>(value: T, pattern: ClosedRange<T>) -> Bool {
    return pattern.contains(value)
}
if case 0.5 = 0.0...1.0 {
    print("自定义约等")
}