swift case

func tsetCase() {
	let points = [(1, 0), (2, 1), (3, 0)]
    for case (let x, let y) in points {
    	print(x, y)
    }
    
    for case let (x, _) in points {
    	print(x)
    }
    
    for case let (x, 0) in points {
    	print(x)
    }
}

可选模式

let ages: [Int?] = [nil, 1, 2, 3, nil, 8]
for case let age? in ages {
	print(age)
}
for item in ages {
	if let age = item {
    	print(age)
    }
}

模式匹配

// ~= 是case的方法
extension String {
	static func ~= (parttern: (String) -> Bool, value: String) -> Bool {
    	parttern(value)
    }
}

// { $0.hasPrefix(prefix) } 等同于 return { (str: String) -> Bool in str.hasPrefix(prefix) }
// prefix == "123"
// str == "123456"
func hasPrefix(_ prefix: String) -> ((String) -> Bool) {
	{ $0.hasPrefix(prefix) }
}

func hasSuffix(_ suffix: String) -> ((String) -> Bool) {
	{ $0.hasSuffix(suffix) }
}

var fn = hasPrefix("123")
print(fn("123456")) // true
print(fn("41236")) // false

var str = "12346"
switch str {
	case hasPrefix("123"): // (String) -> Bool
    	print("以123开头")
    case hasSuffix("123"): // (String) -> Bool
    	print("以123结尾")
    case default:
    	break
}