根据 Swift 中的字符串计算 UILabel 的大小

Question

我正在尝试根据不同的字符串长度计算 UILabel 的高度。

func calculateContentHeight() -> CGFloat{
    var maxLabelSize: CGSize = CGSizeMake(frame.size.width - 48, CGFloat(9999))
    var contentNSString = contentText as NSString
    var expectedLabelSize = contentNSString.boundingRectWithSize(maxLabelSize, options: NSStringDrawingOptions.UsesLineFragmentOrigin, attributes: [NSFontAttributeName: UIFont.systemFontOfSize(16.0)], context: nil)
    print("\(expectedLabelSize)")
    return expectedLabelSize.size.height

}

以上是我用来确定高度的当前函数，但它不起作用。我将不胜感激我能得到的任何帮助。我更喜欢 Swift 中的答案而不是 Objective C.

Answer 1

在String

上使用扩展

Swift 3

extension String {
    func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
    
        return ceil(boundingBox.height)
    }

    func width(withConstrainedHeight height: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: .greatestFiniteMagnitude, height: height)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)

        return ceil(boundingBox.width)
    }
}

还有 NSAttributedString（有时非常有用）

extension NSAttributedString {
    func height(withConstrainedWidth width: CGFloat) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil)
    
        return ceil(boundingBox.height)
    }

    func width(withConstrainedHeight height: CGFloat) -> CGFloat {
        let constraintRect = CGSize(width: .greatestFiniteMagnitude, height: height)
        let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil)
    
        return ceil(boundingBox.width)
    }
}

Swift 4 & 5

只需在 extension String 方法中更改 attributes 的值

来自

[NSFontAttributeName: font]

至

[.font : font]

Answer 2

对于多行文本，此答案无法正常工作。您可以使用 UILabel

构建不同的字符串扩展

extension String {
func height(constraintedWidth width: CGFloat, font: UIFont) -> CGFloat {
    let label =  UILabel(frame: CGRect(x: 0, y: 0, width: width, height: .greatestFiniteMagnitude))
    label.numberOfLines = 0
    label.text = self
    label.font = font
    label.sizeToFit()

    return label.frame.height
 }
}

UILabel 获得固定宽度，.numberOfLines 设置为 0。通过添加文本并调用 .sizeToFit()，它会自动调整到正确的高度。

代码写在Swift3

Answer 3

@IBOutlet weak var constraintTxtV: NSLayoutConstraint!
func TextViewDynamicallyIncreaseSize() {
    let contentSize = self.txtVDetails.sizeThatFits(self.txtVDetails.bounds.size)
    let higntcons = contentSize.height
    constraintTxtV.constant = higntcons
}

Answer 4

extension String{

    func widthWithConstrainedHeight(_ height: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: CGFloat.greatestFiniteMagnitude, height: height)

        let boundingBox = self.boundingRect(with: constraintRect, options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)

        return ceil(boundingBox.width)
    }

    func heightWithConstrainedWidth(_ width: CGFloat, font: UIFont) -> CGFloat? {
        let constraintRect = CGSize(width: width, height: CGFloat.greatestFiniteMagnitude)
        let boundingBox = self.boundingRect(with: constraintRect, options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)

        return ceil(boundingBox.height)
    }

}

Answer 5

这是我在 Swift 4.1 和 Xcode 9.4.1

中的回答

//This is your label
let proNameLbl = UILabel(frame: CGRect(x: 0, y: 20, width: 300, height: height))
proNameLbl.text = "This is your text"
proNameLbl.font = UIFont.systemFont(ofSize: 17)
proNameLbl.numberOfLines = 0
proNameLbl.lineBreakMode = .byWordWrapping
infoView.addSubview(proNameLbl)

//Function to calculate height for label based on text
func heightForView(text:String, font:UIFont, width:CGFloat) -> CGFloat {
    let label:UILabel = UILabel(frame: CGRect(x: 0, y: 0, width: width, height: CGFloat.greatestFiniteMagnitude))
    label.numberOfLines = 0
    label.lineBreakMode = NSLineBreakMode.byWordWrapping
    label.font = font
    label.text = text

    label.sizeToFit()
    return label.frame.height
}

现在你调用这个函数

//Call this function
let height = heightForView(text: "This is your text", font: UIFont.systemFont(ofSize: 17), width: 300)
print(height)//Output : 41.0

Answer 6

我发现接受的答案适用于固定宽度，但不适用于固定高度。对于固定高度，它只会增加宽度以适合一行中的所有内容，除非文本中有换行符。

宽度函数多次调用高度函数，但这是一个快速计算，我没有注意到在 UITable 的行中使用该函数的性能问题。

extension String {

    public func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [.font : font], context: nil)

        return ceil(boundingBox.height)
    }

    public func width(withConstrainedHeight height: CGFloat, font: UIFont, minimumTextWrapWidth:CGFloat) -> CGFloat {

        var textWidth:CGFloat = minimumTextWrapWidth
        let incrementWidth:CGFloat = minimumTextWrapWidth * 0.1
        var textHeight:CGFloat = self.height(withConstrainedWidth: textWidth, font: font)

        //Increase width by 10% of minimumTextWrapWidth until minimum width found that makes the text fit within the specified height
        while textHeight > height {
            textWidth += incrementWidth
            textHeight = self.height(withConstrainedWidth: textWidth, font: font)
        }
        return ceil(textWidth)
    }
}

Answer 7

检查标签文本高度，正在处理

let labelTextSize = ((labelDescription.text)! as NSString).boundingRect(
                with: CGSize(width: labelDescription.frame.width, height: .greatestFiniteMagnitude),
                options: .usesLineFragmentOrigin,
                attributes: [.font: labelDescription.font],
                context: nil).size
            if labelTextSize.height > labelDescription.bounds.height {
                viewMoreOrLess.hide(byHeight: false)
                viewLess.hide(byHeight: false)
            }
            else {
                viewMoreOrLess.hide(byHeight: true)
                viewLess.hide(byHeight: true)

            }

Answer 8

这是一个对我有用的简单解决方案...类似于发布的其他一些解决方案，但它不包括调用 sizeToFit

的需要

注意这是写在Swift5

let lbl = UILabel()
lbl.numberOfLines = 0
lbl.font = UIFont.systemFont(ofSize: 12) // make sure you set this correctly 
lbl.text = "My text that may or may not wrap lines..."

let width = 100.0 // the width of the view you are constraint to, keep in mind any applied margins here

let height = lbl.systemLayoutSizeFitting(CGSize(width: width, height: UIView.layoutFittingCompressedSize.height), withHorizontalFittingPriority: .required, verticalFittingPriority: .fittingSizeLevel).height

这处理换行等。不是最优雅的代码，但它完成了工作。

Answer 9

此解决方案将有助于在运行时计算高度和宽度。

    let messageText = "Your Text String"
    let size = CGSize.init(width: 250, height: 1000)
    let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
    let estimateFrame = NSString(string: messageText).boundingRect(with:  size, options: options, attributes: [NSAttributedString.Key.font: UIFont(name: "HelveticaNeue", size: 17)!], context: nil)

在这里您可以计算字符串的估计高度并将其传递给 UILabel 框架。

estimateFrame.Width
estimateFrame.Height

Answer 10

Swift 5:

如果你有 UILabel 但 boundingRect 不适合你（我遇到过这个问题。它总是返回 1 行高。）有一个扩展可以轻松计算标签大小。

extension UILabel {
    func getSize(constrainedWidth: CGFloat) -> CGSize {
        return systemLayoutSizeFitting(CGSize(width: constrainedWidth, height: UIView.layoutFittingCompressedSize.height), withHorizontalFittingPriority: .required, verticalFittingPriority: .fittingSizeLevel)
    }
}

你可以这样使用它：

let label = UILabel()
label.text = "My text\nIs\nAwesome"
let labelSize = label.getSize(constrainedWidth:200.0)

适合我

Answer 11

在Swift 5:

label.textRect(forBounds: label.bounds, limitedToNumberOfLines: 1)

顺便说一句，limitedToNumberOfLines 的值取决于您想要的标签文本行。

Answer 12

我无法让@KaanDedeoglu 的解决方案在 Swift 5 中用于多行标签和文本视图 - 无论出于何种原因 - 所以我最后写了'by hand' 解决方案保持与@KaanDedeoglu 对感兴趣的人的回答中相同的函数签名。在我的程序中的使用就像一个魅力。

宽度

extension String {

    func width(withConstrainedHeight height: CGFloat, font: UIFont) -> CGFloat {
        
        var wordBoxes = [CGSize]()
        var calculatedHeight = CGFloat.zero
        var calculatedWidth = CGFloat.zero
        
        for word in self.wordsWithWordSeparators() {
            
            let box = word.boundingRect(with: CGSize.zero, attributes: [.font: font], context: nil)
            let boxSize = CGSize(width: box.width, height: box.height)
            wordBoxes.append(boxSize)
            calculatedHeight += boxSize.height
            calculatedWidth = calculatedWidth < boxSize.width ? boxSize.width : calculatedWidth
        }
        
        while calculatedHeight > height && wordBoxes.count > 1 {
            
            var bestLineToRelocate = wordBoxes.count - 1
            
            for i in 1..<wordBoxes.count {
                
                let bestPotentialWidth = wordBoxes[bestLineToRelocate - 1].width + wordBoxes[bestLineToRelocate].width
                let thisPotentialWidth = wordBoxes[i - 1].width + wordBoxes[i].width
                
                if bestPotentialWidth > thisPotentialWidth {
                    bestLineToRelocate = i
                }
            }
            
            calculatedHeight -= wordBoxes[bestLineToRelocate].height
            wordBoxes[bestLineToRelocate - 1].width += wordBoxes[bestLineToRelocate].width
            wordBoxes.remove(at: bestLineToRelocate)
            calculatedWidth = max(wordBoxes[bestLineToRelocate - 1].width, calculatedWidth)
        }
        
        return ceil(calculatedWidth)
    }
}

身高

extension String {
    
    func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
        
        var wordBoxes = [CGSize]()
        var calculatedHeight = CGFloat.zero
        var currentLine = 0
        
        for word in self.wordsWithWordSeparators() {
            
            let box = word.boundingRect(with: CGSize.zero, attributes: [.font: font], context: nil)
            let boxSize = CGSize(width: box.width, height: box.height)
            
            if wordBoxes.isEmpty == true {
                wordBoxes.append(boxSize)
            }
            else if wordBoxes[currentLine].width + boxSize.width > width {
                wordBoxes.append(boxSize)
                currentLine += 1
            }
            else {
                wordBoxes[currentLine].width += boxSize.width
                wordBoxes[currentLine].height = max(wordBoxes[currentLine].height, boxSize.height)
            }
        }
        
        for wordBox in wordBoxes {
            calculatedHeight += wordBox.height
        }
        
        return calculatedHeight
    }
}

使用的辅助方法

extension String {
    
    // Should work with any language supported by Apple
    func wordsWithWordSeparators () -> [String] {
        
        let range = self.startIndex..<self.endIndex
        var words = [String]()
        
        self.enumerateSubstrings(in: range, options: .byWords) { (substr, substrRange, enclosingRange, stop) in
            let wordWithWordSeparators = String(self[enclosingRange])
            words.append(wordWithWordSeparators)
        }
        
        return words
    }
}

注意：这些高度和宽度计算假设给定的标签或文本视图在执行换行时不会拆分或连字符。如果您不是这种情况，您只需要用单词代替字符。此外，如果您处于对运行时敏感的环境中，可能需要考虑限制这些函数调用或缓存结果，因为它们可能会有点昂贵，具体取决于字符串包含的单词数量。

根据 Swift 中的字符串计算 UILabel 的大小

Figure out size of UILabel based on String in Swift

string

iphone

uilabel

ios

swift3

Swift 3

Swift 4 & 5

宽度

身高

使用的辅助方法