它是2015。我不得不去找一篇博客文章来解释如何在最新版本的iOS和XCode中使用Swift，这样它就可以与多行代码一起工作。

将“自动收缩”设置为“最小字体大小”。 将字体设置为理想的最大字体大小(我选择了20) 将“换行”从“换行”改为“截尾”。

来源: http://beckyhansmeyer.com/2015/04/09/autoshrinking-text-in-a-multiline-uilabel/

根据@Eyal Ben Dov的回答，你可能想要创建一个类别，以便在你的其他应用中灵活使用。

奥林匹克广播服务公司。:我已经更新了他的代码，使其与iOS 7兼容

筒式水管文件

#import <UIKit/UIKit.h>

@interface UILabel (DynamicFontSize)

-(void) adjustFontSizeToFillItsContents;

@end

实现文件

#import "UILabel+DynamicFontSize.h"

@implementation UILabel (DynamicFontSize)

#define CATEGORY_DYNAMIC_FONT_SIZE_MAXIMUM_VALUE 35
#define CATEGORY_DYNAMIC_FONT_SIZE_MINIMUM_VALUE 3

-(void) adjustFontSizeToFillItsContents
{
    NSString* text = self.text;

    for (int i = CATEGORY_DYNAMIC_FONT_SIZE_MAXIMUM_VALUE; i>CATEGORY_DYNAMIC_FONT_SIZE_MINIMUM_VALUE; i--) {

        UIFont *font = [UIFont fontWithName:self.font.fontName size:(CGFloat)i];
        NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:text attributes:@{NSFontAttributeName: font}];

        CGRect rectSize = [attributedText boundingRectWithSize:CGSizeMake(self.frame.size.width, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin context:nil];

        if (rectSize.size.height <= self.frame.size.height) {
            self.font = [UIFont fontWithName:self.font.fontName size:(CGFloat)i];
            break;
        }
    }

}

@end

使用

#import "UILabel+DynamicFontSize.h"

[myUILabel adjustFontSizeToFillItsContents];

干杯

这是一个快速扩展UILabel。它运行一个二进制搜索算法，根据标签边界的宽度和高度调整字体大小。测试工作与iOS 9和自动布局。

用法:<label>是预定义的需要调整字体大小的UILabel

<label>.fitFontForSize()

默认情况下，该函数在5pt和300pt的字体大小范围内搜索，并将字体设置为“完全”适合其文本的范围(精确到1.0pt)。你可以定义参数，这样，例如，它在1pt和标签当前字体大小之间精确搜索0.1pts，如下所示:

<label>.fitFontForSize(1.0, maxFontSize: <label>.font.pointSize, accuracy:0.1)

复制/粘贴以下代码到您的文件中

extension UILabel {

    func fitFontForSize(var minFontSize : CGFloat = 5.0, var maxFontSize : CGFloat = 300.0, accuracy : CGFloat = 1.0) {
        assert(maxFontSize > minFontSize)
        layoutIfNeeded() // Can be removed at your own discretion
        let constrainedSize = bounds.size
        while maxFontSize - minFontSize > accuracy {
            let midFontSize : CGFloat = ((minFontSize + maxFontSize) / 2)
            font = font.fontWithSize(midFontSize)
            sizeToFit()
            let checkSize : CGSize = bounds.size
            if  checkSize.height < constrainedSize.height && checkSize.width < constrainedSize.width {
                minFontSize = midFontSize
            } else {
                maxFontSize = midFontSize
            }
        }
        font = font.fontWithSize(minFontSize)
        sizeToFit()
        layoutIfNeeded() // Can be removed at your own discretion
    }

}

注意:每个layoutIfNeeded()调用都可以自行删除

下面是一个UILabel子类的填充代码，它实现了动画字体大小的改变:

@interface SNTextLayer : CATextLayer

@end

@implementation SNTextLayer

- (void)drawInContext:(CGContextRef)ctx {
    // We override this to make text appear at the same vertical positon as in UILabel
    // (otherwise it's shifted tdown)
    CGFloat height = self.bounds.size.height;
    float fontSize = self.fontSize;
    // May need to adjust this somewhat if it's not aligned perfectly in your implementation
    float yDiff = (height-fontSize)/2 - fontSize/10;

    CGContextSaveGState(ctx);
    CGContextTranslateCTM(ctx, 0.0, yDiff);
    [super drawInContext:ctx];
     CGContextRestoreGState(ctx);
}

@end

@interface SNAnimatableLabel ()

@property CATextLayer* textLayer;

@end

@interface SNAnimatableLabel : UILabel

- (void)animateFontToSize:(CGFloat)fontSize withDuration:(double)duration;

@end



@implementation SNAnimatableLabel


- (void)awakeFromNib {
    [super awakeFromNib];
    _textLayer = [SNTextLayer new];
    _textLayer.backgroundColor = self.backgroundColor.CGColor;
    _textLayer.foregroundColor = self.textColor.CGColor;
    _textLayer.font = CGFontCreateWithFontName((CFStringRef)self.font.fontName);
    _textLayer.frame = self.bounds;
    _textLayer.string = self.text;
    _textLayer.fontSize = self.font.pointSize;
    _textLayer.contentsScale = [UIScreen mainScreen].scale;
    [_textLayer setPosition: CGPointMake(CGRectGetMidX(_textLayer.frame), CGRectGetMidY(_textLayer.frame))];
    [_textLayer setAnchorPoint: CGPointMake(0.5, 0.5)];
    [_textLayer setAlignmentMode: kCAAlignmentCenter];
    self.textColor = self.backgroundColor;
    // Blend text with background, so that it doens't interfere with textlayer text
    [self.layer addSublayer:_textLayer];
    self.layer.masksToBounds = NO;
}

- (void)setText:(NSString *)text {
    _textLayer.string = text;
    super.text = text;
}

- (void)layoutSubviews {
    [super layoutSubviews];
    // Need to enlarge the frame, otherwise the text may get clipped for bigger font sizes
    _textLayer.frame = CGRectInset(self.bounds, -5, -5);
}

- (void)animateFontToSize:(CGFloat)fontSize withDuration:(double)duration {
    [CATransaction begin];
    [CATransaction setAnimationDuration:duration];
    _textLayer.fontSize = fontSize;
    [CATransaction commit];
}

Swift 2.0版本:

private func adapteSizeLabel(label: UILabel, sizeMax: CGFloat) {
     label.numberOfLines = 0
     label.lineBreakMode = NSLineBreakMode.ByWordWrapping
     let maximumLabelSize = CGSizeMake(label.frame.size.width, sizeMax);
     let expectSize = label.sizeThatFits(maximumLabelSize)
     label.frame = CGRectMake(label.frame.origin.x, label.frame.origin.y, expectSize.width, expectSize.height)
}

这个解决方案适用于多线:

在学习了几篇文章之后，我需要一个函数来自动缩放文本并调整行数以最适合给定的标签大小，于是我自己编写了一个函数。(即。短字符串可以很好地放在一行上，并使用大量的标签框架，而长字符串会自动分成2或3行，并相应地调整大小)

您可以自由地重新使用它并根据需要进行调整。确保在viewDidLayoutSubviews完成之后调用它，这样初始标签帧就已经设置好了。

+ (void)setFontForLabel:(UILabel *)label withMaximumFontSize:(float)maxFontSize andMaximumLines:(int)maxLines {
    int numLines = 1;
    float fontSize = maxFontSize;
    CGSize textSize; // The size of the text
    CGSize frameSize; // The size of the frame of the label
    CGSize unrestrictedFrameSize; // The size the text would be if it were not restricted by the label height
    CGRect originalLabelFrame = label.frame;

    frameSize = label.frame.size;
    textSize = [label.text sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize: fontSize]}];

    // Work out the number of lines that will need to fit the text in snug
    while (((textSize.width / numLines) / (textSize.height * numLines) > frameSize.width / frameSize.height) && (numLines < maxLines)) {
        numLines++;
    }

    label.numberOfLines = numLines;

    // Get the current text size
    label.font = [UIFont systemFontOfSize:fontSize];
    textSize = [label.text boundingRectWithSize:CGSizeMake(frameSize.width, CGFLOAT_MAX)
                                        options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)
                                     attributes:@{NSFontAttributeName : label.font}
                                        context:nil].size;

    // Adjust the frame size so that it can fit text on more lines
    // so that we do not end up with truncated text
    label.frame = CGRectMake(label.frame.origin.x, label.frame.origin.y, label.frame.size.width, label.frame.size.width);

    // Get the size of the text as it would fit into the extended label size
    unrestrictedFrameSize = [label textRectForBounds:CGRectMake(0, 0, label.bounds.size.width, CGFLOAT_MAX) limitedToNumberOfLines:numLines].size;

    // Keep reducing the font size until it fits
    while (textSize.width > unrestrictedFrameSize.width || textSize.height > frameSize.height) {
        fontSize--;
        label.font = [UIFont systemFontOfSize:fontSize];
        textSize = [label.text boundingRectWithSize:CGSizeMake(frameSize.width, CGFLOAT_MAX)
                                            options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)
                                         attributes:@{NSFontAttributeName : label.font}
                                            context:nil].size;
        unrestrictedFrameSize = [label textRectForBounds:CGRectMake(0, 0, label.bounds.size.width, CGFLOAT_MAX) limitedToNumberOfLines:numLines].size;
    }

    // Set the label frame size back to original
    label.frame = originalLabelFrame;
}