arrays - 快速从数组中获取值并使用递归函数将它们放入另一个数组

Question

我想从一个数组中获取值，并使用递归函数将它们放入另一个数组中。并且要注意我不想使用循环(如“for in loop”)

var rudics = ["one", "two", "three", "four", "five", "six"]
var array = [""]
func changeArray (var new:[String]) {
    array = [new.first!]
    if new.count > 0 {
    new.removeLast()
    changeArray(new)
    }
}

changeArray(rudics)

它给我一个错误

fatal error: unexpectedly found nil while unwrapping an Optional value
Playground execution failed: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).

等等..

请帮帮我!

Answer 1

你可能会考虑这样的事情:

var rudics = ["one", "two", "three", "four", "five", "six"]
var array = [String]()
func changeArray (var new:[String]) {
    if let first = new.first {
        array.append(first)
        new.removeAtIndex(0)
        changeArray(new)
    }
}

changeArray(rudics)