swift 每四位 分隔 字符串

ios - 如何在 swift 中每 N 个字符处为字符串添加分隔符？ 

我有一个包含二进制数字的字符串。如何将它分成一对数字？

假设字符串是:

letx ="11231245"

我想在每 2 个字符后添加一个分隔符，例如“:”(即冒号)。

我希望输出为:

"11:23:12:45"

我怎么能在 Swift 中做到这一点？

最佳答案

Swift 5.2 • Xcode 11.4 或更高版本

extension Collection {

    func unfoldSubSequences(limitedTo maxLength: Int) -> UnfoldSequence {

        sequence(state: startIndex) { start in

            guardstart else{returnnil}

            letend =index(start,offsetBy: maxLength,limitedBy:endIndex) ??endIndex

            defer{ start = end }

            returnself[start..

        }

    }

    func every(n: Int) -> UnfoldSequence {

        sequence(state: startIndex) { index in

            guardindex else{returnnil}

            defer{let_ =formIndex(&index,offsetBy: n,limitedBy:endIndex) }

            returnself[index]

        }

    }

    var pairs: [SubSequence] { .init(unfoldSubSequences(limitedTo: 2)) }

}

extension StringProtocol where Self: RangeReplaceableCollection {

    mutatingfuncinsert(separator: S,everyn:Int) {

        forindexinindices.every(n: n).dropFirst().reversed() {

            insert(contentsOf: separator,at: index)

        }

    }

    funcinserting(separator: S,everyn:Int) ->Self{

        .init(unfoldSubSequences(limitedTo: n).joined(separator: separator))

    }

}

测试

letstr ="112312451"letfinal0= str.unfoldSubSequences(limitedTo:2).joined(separator:":")print(final0)      //"11:23:12:45:1"letfinal1= str.pairs.joined(separator:":")print(final1)      //"11:23:12:45:1"letfinal2= str.inserting(separator:":", every:2)print(final2)      //"11:23:12:45:1\n"varstr2="112312451"str2.insert(separator:":", every:2)print(str2)  //"11:23:12:45:1\n"varstr3="112312451"str3.insert(separator:":", every:3)print(str3)  //"112:312:451\n"varstr4="112312451"str4.insert(separator:":", every:4)print(str4)  //"1123:1245:1\n"