调整UILabel的大小以适应换行符

以下是我发现的最优雅(但有点粗俗)的方法:

3. 减小字符串的大小,直到每个单词都排成一行

资源消耗是足够低的,即使在 UITableViews

新代码如下:

//Set the text  
self.textLabel.text = text;
//Largest size used  
NSInteger fsize = 200;  textLabel.font = [UIFont fontWithName:@"Verdana-Bold"
                                                         size:fsize];

//Calculate size of the rendered string with the current parameters
float height = 
      [text sizeWithFont:textLabel.font
       constrainedToSize:CGSizeMake(textLabel.bounds.size.width,99999) 
           lineBreakMode:UILineBreakModeWordWrap].height;

//Reduce font size by 5 while too large, break if no height (empty string)
while (height > textLabel.bounds.size.height and height != 0) {   
    fsize -= 5;  
    textLabel.font = [UIFont fontWithName:@"Verdana-Bold" size:fsize];   
    height = [text sizeWithFont:textLabel.font 
              constrainedToSize:CGSizeMake(textLabel.bounds.size.width,99999) 
                  lineBreakMode:UILineBreakModeWordWrap].height;
};

// Loop through words in string and resize to fit
for (NSString *word in [text componentsSeparatedByString:@" "]) {
    float width = [word sizeWithFont:textLabel.font].width;
    while (width > textLabel.bounds.size.width and width != 0) {
        fsize -= 3;
        textLabel.font = [UIFont fontWithName:@"Verdana-Bold" size:fsize];
        width = [word sizeWithFont:textLabel.font].width;

    }
}

下面是我对0x90在某个类别中的答案的版本:

@implementation UILabel (MultilineAutosize)

- (void)adjustFontSizeToFit
{
    //Largest size used
    NSInteger fsize = self.font.pointSize;

    //Calculate size of the rendered string with the current parameters
    float height = [self.text sizeWithFont:self.font
                         constrainedToSize:CGSizeMake(self.bounds.size.width, MAXFLOAT)
                             lineBreakMode:NSLineBreakByWordWrapping].height;

    //Reduce font size by 5 while too large, break if no height (empty string)
    while (height > self.bounds.size.height && height > 0) {
        fsize -= 5;
        self.font = [self.font fontWithSize:fsize];
        height = [self.text sizeWithFont:self.font
                       constrainedToSize:CGSizeMake(self.bounds.size.width, MAXFLOAT)
                           lineBreakMode:NSLineBreakByWordWrapping].height;
    };

    // Loop through words in string and resize to fit
    for (NSString *word in [self.text componentsSeparatedByString:@" "]) {
        float width = [word sizeWithFont:self.font].width;
        while (width > self.bounds.size.width && width > 0) {
            fsize -= 3;
            self.font = [self.font fontWithSize:fsize];
            width = [word sizeWithFont:self.font].width;
        }
    }
}

@end

UILabel+AdjustFontSize.h

@interface UILabel (UILabel_AdjustFontSize)

- (void) adjustsFontSizeToFitWidthWithMultipleLinesFromFontWithName:(NSString*)fontName size:(NSInteger)fsize andDescreasingFontBy:(NSInteger)dSize;

@end

@implementation UILabel (UILabel_AdjustFontSize)

- (void) adjustsFontSizeToFitWidthWithMultipleLinesFromFontWithName:(NSString*)fontName size:(NSInteger)fsize andDescreasingFontBy:(NSInteger)dSize{

    //Largest size used  
    self.font = [UIFont fontWithName:fontName size:fsize];

    //Calculate size of the rendered string with the current parameters
    float height = [self.text sizeWithFont:self.font
                    constrainedToSize:CGSizeMake(self.bounds.size.width,99999) 
                        lineBreakMode:UILineBreakModeWordWrap].height;

    //Reduce font size by dSize while too large, break if no height (empty string)
    while (height > self.bounds.size.height && height != 0) {   
        fsize -= dSize;
        self.font = [UIFont fontWithName:fontName size:fsize];   
        height = [self.text sizeWithFont:self.font 
                  constrainedToSize:CGSizeMake(self.bounds.size.width,99999) 
                      lineBreakMode:UILineBreakModeWordWrap].height;
    };

    // Loop through words in string and resize to fit
    for (NSString *word in [self.text componentsSeparatedByString:@" "]) {
        float width = [word sizeWithFont:self.font].width;
        while (width > self.bounds.size.width && width != 0) {
            fsize -= dSize;
            self.font = [UIFont fontWithName:fontName size:fsize];
            width = [word sizeWithFont:self.font].width;            
        }
    }
}

@end

这是一个很好的问题,你会认为使用尽可能大的字体大小而不拆分单词将是内置的一部分 UIKit 功能或相关框架。下面是这个问题的一个很好的视觉例子:

正如其他人所描述的,技巧是对单个单词以及整个文本执行大小搜索。这是因为,当您指定要绘制单个单词的宽度时,大小调整方法会将单词拆分,因为它们没有其他选择—您要求它们将具有特定字体大小的“不可拆分”字符串绘制到根本不适合的区域中。

在我的工作方案的核心,我使用以下二进制搜索函数:

func binarySearch(string: NSAttributedString, minFontSize: CGFloat, maxFontSize: CGFloat, maxSize: CGSize, options: NSStringDrawingOptions) -> CGFloat {
    let avgSize = roundedFontSize((minFontSize + maxFontSize) / 2)
    if avgSize == minFontSize || avgSize == maxFontSize { return minFontSize }
    let singleLine = !options.contains(.usesLineFragmentOrigin)
    let canvasSize = CGSize(width: singleLine ? .greatestFiniteMagnitude : maxSize.width, height: .greatestFiniteMagnitude)
    if maxSize.contains(string.withFontSize(avgSize).boundingRect(with: canvasSize, options: options, context: nil).size) {
      return binarySearch(string: string, minFontSize:avgSize, maxFontSize:maxFontSize, maxSize: maxSize, options: options)
    } else {
      return binarySearch(string: string, minFontSize:minFontSize, maxFontSize:avgSize, maxSize: maxSize, options: options)
    }
  }

如果您只关心以一种简单的方式在屏幕上显示文本,那么我已经用Swift开发了一个健壮的实现,我还在一个生产应用程序中使用它。它是一个 UIView 为任何输入文本(包括多行)提供高效、自动字体缩放的子类。要使用它,您只需执行以下操作:

let view = AKTextView()
// Use a simple or fancy NSAttributedString
view.attributedText = .init(string: "Some text here")
// Add to the view hierarchy somewhere

就这样!您可以在此处找到完整的源代码: https://github.com/FlickType/AccessibilityKit

func adjustFontSizeToFit() {
    guard var font = self.font, let text = self.text else { return }
    let size = self.frame.size
    var maxSize = font.pointSize
    while maxSize >= self.minimumScaleFactor * self.font.pointSize {
        font = font.withSize(maxSize)
        let constraintSize = CGSize(width: size.width, height: CGFloat.greatestFiniteMagnitude)
        let textRect = (text as NSString).boundingRect(with: constraintSize, options: .usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font : font], context: nil)
        let labelSize = textRect.size
        if labelSize.height <= size.height {
            self.font = font
            self.setNeedsLayout()
            break
        }
        maxSize -= 1
    }
    self.font = font;
    self.setNeedsLayout()
}