在启用自动缩小到最小字体大小的情况下检测 UILabel 的点击

【问题标题】：Detect tap for UILabel with Autoshrink to minimum font size enabled在启用自动缩小到最小字体大小的情况下检测 UILabel 的点击
【发布时间】：2020-08-22 09:13:59
【问题描述】：

我正在使用我修改的以下 UITapGestureRecognizer，以便其他人可以复制和粘贴以查看与我相同的输出。

extension UITapGestureRecognizer {

    func didTapAttributedTextInLabel(label: UILabel, inRange targetRange: NSRange) -> Bool {
        // Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
        let layoutManager = NSLayoutManager()
        let textContainer = NSTextContainer(size: CGSize.zero)

        //let mutableAttribString = NSMutableAttributedString(attributedString: label.attributedText!)
        //mutableAttribString.addAttributes([NSAttributedString.Key.font: label.font!], range: NSRange(location: 0, length: label.attributedText!.length))

        let textStorage = NSTextStorage(attributedString: label.attributedText!)
        //let textStorage = NSTextStorage(attributedString: mutableAttribString)

        // Configure layoutManager and textStorage
        layoutManager.addTextContainer(textContainer)
        textStorage.addLayoutManager(layoutManager)

        // Configure textContainer
        textContainer.lineFragmentPadding = 0.0
        textContainer.lineBreakMode = label.lineBreakMode
        textContainer.maximumNumberOfLines = label.numberOfLines

        let labelSize = label.bounds.size
        print("LabelSize=",labelSize)

        textContainer.size = labelSize
        print("TextContainerSize=",textContainer.size)

        // Find the tapped character location and compare it to the specified range
        let locationOfTouchInLabel = self.location(in: label)
        print("LocationOfTouchInLabel=",locationOfTouchInLabel)

        let textBoundingBox = layoutManager.usedRect(for: textContainer)
        print("TextBoundingBox=",textBoundingBox)
        //let textContainerOffset = CGPointMake((labelSize.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x,
                                              //(labelSize.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y);
        let textContainerOffset = CGPoint(x: (labelSize.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x, y: (labelSize.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y)
        print("textContainerOffset",textContainerOffset)

        //let locationOfTouchInTextContainer = CGPointMake(locationOfTouchInLabel.x - textContainerOffset.x,
                                                        // locationOfTouchInLabel.y - textContainerOffset.y);
        let locationOfTouchInTextContainer = CGPoint(x: locationOfTouchInLabel.x - textContainerOffset.x, y: locationOfTouchInLabel.y - textContainerOffset.y)
        print("LocationOfTouchInTextContainer",locationOfTouchInTextContainer)

        let indexOfCharacter = layoutManager.characterIndex(for: locationOfTouchInTextContainer, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
        print("IndexOfCharacter=",indexOfCharacter)

        print("TargetRange=",targetRange)
        return NSLocationInRange(indexOfCharacter, targetRange)
    }

}

我这样设置标签以检测其他答案所说的点击：

formulaLabel.addGestureRecognizer(UITapGestureRecognizer(target:self, action: #selector(tapLabel(gesture:))))

设置为属性化。

如果重要的话，我有以下代码可以用文本执行动画。

func doFormulaAnimation(){
        //animTimer = Timer.scheduledTimer(withTimeInterval: 0.3, repeats: true, block: {_ in
            //Draw correct formula based on mode.

        var formula = ""
        var highlight_ranges:[NSRange] = []

        if(stateController?.tdfvariables.ebrtMode == true){
            formulaLabel.numberOfLines = 1
            formula = "BED = N * d * [ RBE + ( d / (α/β) ) ]"

            self.formulaLabel.attributedText = NSMutableAttributedString(string: formula, attributes: [ NSAttributedString.Key.foregroundColor: UIColor.label ])

            if(self.dosePerFractionSelected==true){
                highlight_ranges.append(NSRange(location: 10, length: 1))
                highlight_ranges.append(NSRange(location: 24, length: 1))
            }

            if(self.alphaBetaSelected==true){
                highlight_ranges.append(NSRange(location: 29, length: 3))
            }

            if(self.totalDoseSelected==true){
                highlight_ranges.append(NSRange(location: 6, length: 5))
            }

            if(self.numFractionsSelected==true){
                highlight_ranges.append(NSRange(location: 6, length: 1))
            }
        }

        if(stateController?.tdfvariables.ldrMode == true){
            formulaLabel.numberOfLines = 3
            formula = "BED = R * T * [RBE + (( g * R * T) / (α/β) ) ]\ng = ( 2 / μT ) * ( 1 - ( ( 1 - exp(-μT) / μT ) )\nμ = 0.693 / Thalf repair"
        }

        if(stateController?.tdfvariables.permMode == true){
            formulaLabel.numberOfLines = 2
            formula = "BED = ( R0 / L ) * [ RBE + ( R0 / ( ( u + L) * (α/β) ) ) ]\n"
        }

        UIView.transition(with: self.formulaLabel, duration: 0.5, options: .transitionCrossDissolve, animations: {
                let colorAttribute = [ NSAttributedString.Key.foregroundColor: UIColor.label ]
                let attributedTextFormula = NSMutableAttributedString(string: formula, attributes: colorAttribute)

                let paragraphStyle = NSMutableParagraphStyle()
                paragraphStyle.lineSpacing = 6
                paragraphStyle.lineBreakMode = .byTruncatingTail
                //paragraphStyle.alignment = .center

                attributedTextFormula.addAttribute(
                    .paragraphStyle,
                    value: paragraphStyle,
                    range: NSRange(location: 0, length: attributedTextFormula.length
                ))


                self.formulaLabel.attributedText = attributedTextFormula
                //
            }, completion: { finished in
                print("finished first transition")

                UIView.transition(with: self.formulaLabel, duration: 0.5, options: .transitionCrossDissolve, animations: {
                    let colorAttribute = [ NSAttributedString.Key.foregroundColor: UIColor.label ]
                    let attributedTextFormula = NSMutableAttributedString(string: formula, attributes: colorAttribute)
                    for range in highlight_ranges {
                        attributedTextFormula.addAttribute(NSAttributedString.Key.foregroundColor, value: UIColor.red, range: range)
                    }

                    let paragraphStyle = NSMutableParagraphStyle()
                    paragraphStyle.lineSpacing = 6
                    paragraphStyle.lineBreakMode = .byTruncatingTail
                    //paragraphStyle.alignment = .center

                    attributedTextFormula.addAttribute(
                        .paragraphStyle,
                        value: paragraphStyle,
                        range: NSRange(location: 0, length: attributedTextFormula.length
                    ))

                    self.formulaLabel.attributedText = attributedTextFormula
                    //self.formulaLabel.addInterlineSpacing(spacingValue: 1)
                }, completion: { finished in
                    print("finished second transition")
                })

        })
    }

上面的代码演示了我相应地创建 NSMutableString 并相应地设置段落样式和行间距（我有预感这可能是问题，但不确定如何测试）等等...

终于有了我的点击标签功能

 @IBAction func tapLabel(gesture: UITapGestureRecognizer) {
        guard let text = formulaLabel.attributedText?.string else {
            return
        }

        let AB_Range = text.range(of: "(α/β)")

        //let AB_Range = NSRange(location: 29, length: 3)
        if gesture.didTapAttributedTextInLabel(label: formulaLabel, inRange: NSRange(AB_Range!, in: text)) {
           print("Tapped a/b")
        } else {
           print("Tapped none")
        }
    }

目前它没有点击正确的位置，但在很大程度上偏离了。调试后，它为什么不工作变得很明显，但我不确定如何修复代码或哪里出错了。

当我点击 A/B 时，我应该得到它作为调试信息。

LabelSize= (315.0, 43.0)
TextContainerSize= (315.0, 43.0)
LocationOfTouchInLabel= (266.0, 28.0)
TextBoundingBox= (0.0, 0.0, 185.373046875, 13.8)
textContainerOffset (64.8134765625, 14.6)
LocationOfTouchInTextContainer (201.1865234375, 13.4)
IndexOfCharacter= 36
TargetRange= {28, 5}
Tapped none

它计算 textbounding box 或 textcontaineroffset 或 locationoftouchintextcontainer 的部分很可能是错误点，但我不确定是哪一个，因为这很难理解。

我可以说它工作不正常，因为在我的字符串中它没有接近结尾，无论我在哪里点击它，它总是说 indexofcharacter=36，这意味着它没有用我上面提到的变量之一正确计算某些东西.

如果他们知道为什么这不起作用，我们将不胜感激。

为了让您了解文本现在的外观，我将在下面向您展示。我的最终目标是做到这一点，以便我可以单击公式中的部分以显示值，因此您可以说可点击的链接。

更新::

我忘了提到当我更新 UITapGestureRecognizer 并添加这些行时：

let mutableAttribString = NSMutableAttributedString(attributedString: label.attributedText!)
        mutableAttribString.addAttributes([NSAttributedString.Key.font: label.font!], range: NSRange(location: 0, length: label.attributedText!.length))

并将其设置为文本存储，let textStorage = NSTextStorage(attributedString: mutableAttribString) 我确实看到数字有所改善，但仍有一段距离。

LabelSize= (315.0, 43.0)
TextContainerSize= (315.0, 43.0)
LocationOfTouchInLabel= (269.0, 25.5)
TextBoundingBox= (7.505859375, 0.0, 299.98828125, 42.9609375)
textContainerOffset (0.0, 0.01953125)
LocationOfTouchInTextContainer (269.0, 25.48046875)
IndexOfCharacter= 17
TargetRange= {28, 5}
Tapped none

您会注意到 textboundingbox 至少更类似于标签大小。我在某处读到，如果您使用不同的字体可能会出现问题，所以这就是为什么我尝试添加它以确保它正常工作。

另外有趣的是，将它添加到 UITapGestureRecognizer 似乎也有帮助：

let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineSpacing = 6
        paragraphStyle.lineBreakMode = .byTruncatingTail
        //paragraphStyle.alignment = .center

    mutableAttribString.addAttribute(
        .paragraphStyle,
        value: paragraphStyle,
        range: NSRange(location: 0, length: mutableAttribString.length
    ))

我注意到当我这样做时文本边界框正确显示 0,0 而不是 7.50

LabelSize= (315.0, 43.0)
TextContainerSize= (315.0, 43.0)
LocationOfTouchInLabel= (262.5, 31.0)
TextBoundingBox= (0.0, 0.0, 299.98828125, 42.9609375)
textContainerOffset (7.505859375, 0.01953125)
LocationOfTouchInTextContainer (254.994140625, 30.98046875)
IndexOfCharacter= 17
TargetRange= {28, 5}
Tapped none

**主要更新*****

好消息！事实证明，字体修复是修复的一部分，但是因为我启用了 autoshrink 并启用了最小字体大小和最大字体大小，所以它从未正确计算！ 当我设置为固定字体大小时，一切正常！

现在的问题是如何使其在启用自动收缩的情况下工作？请注意，您必须将大小设置为非常大的值才能证明这有效，例如我将我的设置为 55，因此它会相应地自动收缩并且然后你会看到错误，如果默认大小更小，那么它似乎工作正常，这告诉我错误可能与最初的大小非常大有关？

【问题讨论】：

    标签： uilabel multiline swift5 autoshrink


    【解决方案1】：

    所以我终于想出了一个可以接受的答案。

    关键是下面的代码：

    let formulaLabelWidth = formulaLabel.bounds.size.width

var font_size:CGFloat = 36.0 //Change this to a higher number if you need to.
var stringSize = NSString(string: formula).size(withAttributes: [.font : self.formulaLabel.font.withSize(font_size)])
while(stringSize.width>formulaLabelWidth){
    font_size = font_size - 1
    stringSize = NSString(string: formula).size(withAttributes: [.font : self.formulaLabel.font.withSize(font_size)])
}


 formulaLabel.font = formulaLabel.font.withSize(font_size)

    这段代码所做的是绘制字符串，就好像它具有特定的字体大小一样，为您提供宽度和高度的边界。就我而言，我只关心宽度，这要归功于您如何在界面构建器中设置 UILabel。

    要使此策略生效，必须在您的 UILabel 上进行设置，因为它会尽一切努力找到适合文本的完美尺寸。

    这确实适用于多行，我在我的许多公式中都使用了它。这些行用 \n 字符分隔并自动计算在内，因为它只是增加了使用.size(withAttributes) 函数绘制的高度。

    他们曾经有一个 sizeForFont 但它已被弃用，所以我研究了这个函数作为一个可能的解决方案，确实它确实可以通过一些聪明的想法工作。

    至于检测点击，请使用我创建的以下修改后的 UITapGestureRecognizer。

    extension UITapGestureRecognizer {

    func didTapAttributedTextInLabel(label: UILabel, inRange targetRange: NSRange) -> Bool {
        // Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
        let layoutManager = NSLayoutManager()
        let textContainer = NSTextContainer(size: CGSize.zero)

        let mutableAttribString = NSMutableAttributedString(attributedString: label.attributedText!)
        mutableAttribString.addAttributes([NSAttributedString.Key.font: label.font!], range: NSRange(location: 0, length: label.attributedText!.length))

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineSpacing = 6
        paragraphStyle.lineBreakMode = .byTruncatingTail
        paragraphStyle.alignment = .center
        mutableAttribString.addAttributes([.paragraphStyle: paragraphStyle], range: NSMakeRange(0, mutableAttribString.string.count))

        let textStorage = NSTextStorage(attributedString: mutableAttribString)

        // Configure textContainer
        textContainer.lineFragmentPadding = 0.0
        textContainer.lineBreakMode = label.lineBreakMode
        textContainer.maximumNumberOfLines = label.numberOfLines

        // Configure layoutManager and textStorage
        layoutManager.addTextContainer(textContainer)

        textStorage.addLayoutManager(layoutManager)

        let labelSize = label.bounds.size

        textContainer.size = labelSize

        // Find the tapped character location and compare it to the specified range
        let locationOfTouchInLabel = self.location(in: label)

        let textBoundingBox = layoutManager.usedRect(for: textContainer)
        //let textContainerOffset = CGPointMake((labelSize.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x,
                                              //(labelSize.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y);
        let textContainerOffset = CGPoint(x: (labelSize.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x, y: (labelSize.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y)

        //let locationOfTouchInTextContainer = CGPointMake(locationOfTouchInLabel.x - textContainerOffset.x,
                                                        // locationOfTouchInLabel.y - textContainerOffset.y);
        let locationOfTouchInTextContainer = CGPoint(x: locationOfTouchInLabel.x - textContainerOffset.x, y: locationOfTouchInLabel.y - textContainerOffset.y)

        let indexOfCharacter = layoutManager.characterIndex(for: locationOfTouchInTextContainer, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
        print("IndexOfCharacter=",indexOfCharacter)

        print("TargetRange=",targetRange)
        return NSLocationInRange(indexOfCharacter, targetRange)
    }

}

    请随意删除 cmets，但我将它们留在那里，以便您可以看到它正在选择正确的字符串索引。

    另外请注意，我在其中设置了一个段落设置，行距为 6，对齐中心，因此请随意将其更改为您的用例，但不要更改换行模式！这对于系统在绘制时自动找到最佳字体大小至关重要。

    在此代码中还引用了当前标签字体，这是我添加的新部分，因为没有它，文本存储计算将与堆栈溢出的其他答案中指出的那样相去甚远。

    将它与点击手势的功能放在一起

    @IBAction func tapLabel(gesture: UITapGestureRecognizer) {
        guard let text = formulaLabel.attributedText?.string else {
            return
        }

        let AB_Range = text.range(of: "(α/β)")

        //let AB_Range = NSRange(location: 29, length: 3)
        if gesture.didTapAttributedTextInLabel(label: formulaLabel, inRange: NSRange(AB_Range!, in: text)) {
           print("Tapped a/b")
        } else {
           print("Tapped none")
        }
    }

    当然还有在 viewDidLoad 或适当的地方将点击手势设置为 UILabel...

    formulaLabel.addGestureRecognizer(UITapGestureRecognizer(target:self, action: #selector(tapLabel(gesture:))))

    你有自己的工作

    • 多行友好
    • 自动收缩友好
    • 可点击友好

    UILabel！

    【讨论】：

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