ios - Swift 中的 String.enumerateSubstringsInRange 停止

Question

首先，感谢 Stonz2 在 Find last visible line index in NSAttributedString's drawWithRect 中的回答

我有类似的麻烦，所以我得到了这个 objective-c 函数。

但我正在使用 swift，当我想将其转换为 swift 时，我遇到了麻烦。

这是我刚刚转换的 Stonz2 答案的快速版本。

func removeLastWord( str:String ) -> String{
    var range = Range(start:count(str), end:0)
    let opts:NSStringEnumerationOptions = .ByWords | .Reverse | .SubstringNotRequired

    // trouble in here,  Cannot invoke 'enumerateSubstringsInRange' with an argument list of type '(Range<Int>, options: NSStringEnumerationOptions, (_, _, _, _) -> ())'
    str.enumerateSubstringsInRange(Range(start:0, end:count(str)), options: opts) {
        (substring, substringRange, enclosingRange, stop) -> () in
        range = substringRange
        stops = true
    }

    return str.substringToIndex(advance(str.startIndex, range.endIndex))
}

func pageSplitIndexForString( string:String, frame:CGRect, font:UIFont ) -> Int {

    let fixedWidth = frame.size.width
    let textView = UITextView()

    textView.text = string
    textView.font = font

    var newSize = CGSizeMake(fixedWidth, CGFloat.max)
    textView.frame.size = newSize
    textView.sizeToFit()
    var newFrame = textView.frame

    println(textView.frame)

    while ( newFrame.height > frame.height ) {
        textView.text = removeLastWord(textView.text)
        newSize = CGSizeMake(fixedWidth, CGFloat.max)
        textView.frame.size = newSize
        textView.sizeToFit()
        // fmaxf fmax?
        newFrame.size = CGSizeMake(fmax(newSize.width, fixedWidth), newSize.height)
    }

    var str = string.substringFromIndex(advance(textView.text.startIndex, count(textView.text)))

    println("Page one text: \(textView.text)")
    println("Page two text: \(str)")

    return (textView.text as NSString).length
}

所以我想知道在 swift 中转换这个 objective-c 函数的正确方法是什么？

Answer 1

你可以使用这个删除最后一个词，

func removeLastWord( str:String ) -> String {

    var start = str.startIndex // Start at the string's start index
    var end = str.endIndex
    var range: Range<String.Index> = Range<String.Index>(start: start,end: end)

    let opts:NSStringEnumerationOptions = .ByWords | .Reverse

    str.enumerateSubstringsInRange(range, options: opts) {

        (substring, substringRange, enclosingRange, stop) -> () in

        range = substringRange
        stop = true
    }

    return str.substringToIndex(range.startIndex)
}