arrays - addObjectsFromArray 错误 : how to convert `Array` to `[AnyObject]` ?

Question

我想转换一个 String至 Array ，然后按 NSCountedSet 计算重复值.

这些代码出错:

    let str = "hello"
    let ar = Array(str.characters)
    let set = NSCountedSet()
    set.addObjectsFromArray(ar)

错误:

 error: cannot convert value of type 'Array<_Element>' (aka 'Array<Character>') to expected argument type '[AnyObject]'
    set.addObjectsFromArray(ar)

我知道原因，那么如何转换Array<Character>至 [AnyObject] ？

Answer 1

不能转换为 AnyObject 的字符。在将字符添加到计数集之前，您需要将其映射到字符串中:

let str = "Hello, playground"
let stringArray = str.characters.map{String($0)}
let countedSet = NSCountedSet()
countedSet.addObjectsFromArray(stringArray)