swift 3 : sorting arrays with sort function: seeing error of Ambiguous use of 'sort(comparator:)'

Question

此代码生成此错误:

Ambiguous use of 'sort(comparator:)'

chars.sort {
    let s0 = $0 as? String
    let s1 = $1 as? String
    if array.index(of: s0) == array.index(of: s1) {
        ComparisonResult.orderedSame
    } else if array.index(of: s0) < array.index(of: s1) {
        ComparisonResult.orderedDescending
    } else {
        ComparisonResult.orderedAscending
    }
}

其他 SO 帖子建议将 sort 函数的参数转换为字符串，但错误仍然存​​在。谁能解释一下为什么？

Answer 1

如果你有这样的数组

let chars: [Any] = ["g", "c", "a"]

并且您想使用元素到另一个数组中的顺序对其进行排序

let orders = ["a", "b", "c", "e", "f"]

你可以简单地写

let sorted = chars
    .flatMap { $0 as? String }
    .sorted { orders.index(of:$0) ?? Int.max < orders.index(of: $1) ?? Int.max }

// print(sorted) 
// ["a", "c", "g"]