如何转换NSRange中的范围？

Question

我正在更新swift 3中的代码.将Range转换为NSRange时出错.如何在swift 3中做到这一点？

func nsRange(_ range : Range<String.Index>) -> NSRange {
    let utf16from = String.UTF16View.Index(range.lowerBound, within: utf16)
    let utf16to   = String.UTF16View.Index(range.upperBound,   within: utf16)
    return NSRange(location: utf16.startIndex.distanceTo(utf16from), length: utf16from.distanceTo(utf16to))
}

Answer 1

Xcode 9•Swift 4

extension RangeExpression where Bound == String.Index  {
    func nsRange<S: StringProtocol>(in string: S) -> NSRange { .init(self, in: string) }
}

let string = "Hello USA  !!! Hello World !!!"
if let nsRange = string.range(of: "Hello World")?.nsRange(in: string) {
    (string as NSString).substring(with: nsRange) //  "Hello World"
}

您还可以创建扩展StringProtocol的相应nsRange(of :)方法,如下所示:

extension StringProtocol {
    func nsRange<S: StringProtocol>(of string: S, options: String.CompareOptions = [], range: Range<Index>? = nil, locale: Locale? = nil) -> NSRange? {
        self.range(of: string,
                   options: options,
                   range: range ?? startIndex..<endIndex,
                   locale: locale ?? .current)?
            .nsRange(in: self)
    }
    func nsRanges<S: StringProtocol>(of string: S, options: String.CompareOptions = [], range: Range<Index>? = nil, locale: Locale? = nil) -> [NSRange] {
        var start = range?.lowerBound ?? startIndex
        let end = range?.upperBound ?? endIndex
        var ranges: [NSRange] = []
        while start < end,
            let range = self.range(of: string,
                                   options: options,
                                   range: start..<end,
                                   locale: locale ?? .current) {
            ranges.append(range.nsRange(in: self))
            start = range.lowerBound < range.upperBound ? range.upperBound :
            index(range.lowerBound, offsetBy: 1, limitedBy: endIndex) ?? endIndex
        }
        return ranges
    }
}

let string = "Hello USA  !!! Hello World !!!"

if let nsRange = string.nsRange(of: "Hello World") {
    (string as NSString).substring(with: nsRange) //  "Hello World"
}
let nsRanges = string.nsRanges(of: "Hello")
print(nsRanges)   // "[{0, 5}, {19, 5}]\n"