无法使用类型为swift 2.0的参数列表调用reduce

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当我将swift 1.2升级到swift 2.0时，会发生以下错误

When i upgrade swift 1.2 to swift 2.0 following error occurs

无法使用类型为

cannot invoke reduce with an argument list of type

这是代码

let escaped = reduce(string, "") { string, character in string + (character == mark ? "\(mark)\(mark)" : "\(character)")

能帮我解决这个问题吗

推荐答案

reduce()是用于数组之类的集合的方法，因此您必须在可以使用的characters属性访问的字符列表中调用它字符串，而不是整个字符串本身:

reduce() is a method for collections such as arrays so you have to call it on the list of the characters you can access using the characters property of the string, not on the whole string itself:

let escaped = string.characters.reduce("") { string, character in string + (character == mark ? "\(mark)\(mark)" : "\(character)") }