2018-07-10swift4与swift 3.3 语法重拾(二)

函数与闭包

//用函数做返回值
func makeIncrementer() -> ((Int) -> Int) {
    func addOne(number: Int) -> Int {
        return 1 + number
    }
    return addOne
}
var increment = makeIncrementer()
increment(7)

//用函数做参数
func hasAnyMatches(list: [Int], condition: (Int) -> Bool) -> Bool {
    for item in list {
        if condition(item) {
            return true
        }
    }
    return false
}
func lessThanTen(number: Int) -> Bool {
    return number < 10
}
var numbers = [20, 19, 7, 12]
hasAnyMatches(list: numbers, condition: lessThanTen)

闭包

var numbers = [20, 19, 7, 12]

numbers.map({
    (number: Int) -> Int in
    let result = 3 * number
    return result
})

let mappedNumbers = numbers.map({ number in 3 * number })
print(mappedNumbers)

let sortedNumbers = numbers.sorted { $0 > $1 }
print(sortedNumbers)