swift list简单使用

1. 截取列表值 (前几个)

    ///     let numbers = [1, 2, 3, 4, 5]

    ///     print(numbers.prefix(2))

    ///     // Prints "[1, 2]"

    ///     print(numbers.prefix(10))

    ///     // Prints "[1, 2, 3, 4, 5]"

2. 截取列表值 (后几个)

    ///     let numbers = [1, 2, 3, 4, 5]

    ///     print(numbers.suffix(2))

    ///     // Prints "[4, 5]"

    ///     print(numbers.suffix(10))

    ///     // Prints "[1, 2, 3, 4, 5]"

3. 获取一个随机的元素

　　let numbers = [1, 2, 3, 4, 5]

　　let number = numbers.randomElement()