这是一个旧的解决方案，在iOS上使用自动布局>=6

我的解决方案：

自行拆分线条（忽略标签换行设置）自己绘制线（忽略标签对齐）

@interface UITopAlignedLabel : UILabel

@end

@implementation UITopAlignedLabel

#pragma mark Instance methods

- (NSArray*)splitTextToLines:(NSUInteger)maxLines {
    float width = self.frame.size.width;

    NSArray* words = [self.text componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    NSMutableArray* lines = [NSMutableArray array];

    NSMutableString* buffer = [NSMutableString string];    
    NSMutableString* currentLine = [NSMutableString string];

    for (NSString* word in words) {
        if ([buffer length] > 0) {
            [buffer appendString:@" "];
        }

        [buffer appendString:word];

        if (maxLines > 0 && [lines count] == maxLines - 1) {
            [currentLine setString:buffer];
            continue;
        }

        float bufferWidth = [buffer sizeWithFont:self.font].width;

        if (bufferWidth < width) {
            [currentLine setString:buffer];
        }
        else {
            [lines addObject:[NSString stringWithString:currentLine]];

            [buffer setString:word];
            [currentLine setString:buffer];
        }
    }

    if ([currentLine length] > 0) {
        [lines addObject:[NSString stringWithString:currentLine]];
    }

    return lines;
}

- (void)drawRect:(CGRect)rect {
    if ([self.text length] == 0) {
        return;
    }

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, self.textColor.CGColor);
    CGContextSetShadowWithColor(context, self.shadowOffset, 0.0f, self.shadowColor.CGColor);

    NSArray* lines = [self splitTextToLines:self.numberOfLines];
    NSUInteger numLines = [lines count];

    CGSize size = self.frame.size;
    CGPoint origin = CGPointMake(0.0f, 0.0f);

    for (NSUInteger i = 0; i < numLines; i++) {
        NSString* line = [lines objectAtIndex:i];

        if (i == numLines - 1) {
            [line drawAtPoint:origin forWidth:size.width withFont:self.font lineBreakMode:UILineBreakModeTailTruncation];            
        }
        else {
            [line drawAtPoint:origin forWidth:size.width withFont:self.font lineBreakMode:UILineBreakModeClip];
        }

        origin.y += self.font.lineHeight;

        if (origin.y >= size.height) {
            return;
        }
    }
}

@end

yourLabel.baselineAdjustment = UIBaselineAdjustmentAlignCenters;

雨燕5

这里是从左上角开始渲染文本，并保持可能调整的文本大小。

final class TopAlignedLabel: UILabel {
  override func drawText(in rect: CGRect) {
    super.drawText(in: .init(
      origin: .zero, 
      size: textRect(
        forBounds: rect, 
        limitedToNumberOfLines: numberOfLines
      ).size
    ))
  }
}

您可以手动更改标签的高度，而不是使用sizeToFit；

CGSize size = [descLabel.text sizeWithFont:descLabel.font constrainedToSize:CGSizeMake(labelWidth, labelHeight)];
CGRect frame = descLabel.frame;
frame.size.height = size.height;    
[yourLabel setFrame:frame];

返回的尺寸将最适合标签的内容。如果标签的高度适合其内容，则内容位于标签中心时不会出现问题。

FXLabel（在github上）通过将label.contentMode设置为UIViewContentModeTop来实现这一点。这个组件不是我制造的，但它是我经常使用的组件，具有大量的功能，而且似乎工作得很好。

我希望有一个标签能够有多行，最小字体大小，并在父视图中水平和垂直居中。我以编程方式将标签添加到视图中：

- (void) customInit {
    // Setup label
    self.label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
    self.label.numberOfLines = 0;
    self.label.lineBreakMode = UILineBreakModeWordWrap;
    self.label.textAlignment = UITextAlignmentCenter;

    // Add the label as a subview
    self.autoresizesSubviews = YES;
    [self addSubview:self.label];
}

然后当我想更改标签的文本时。。。

- (void) updateDisplay:(NSString *)text {
    if (![text isEqualToString:self.label.text]) {
        // Calculate the font size to use (save to label's font)
        CGSize textConstrainedSize = CGSizeMake(self.frame.size.width, INT_MAX);
        self.label.font = [UIFont systemFontOfSize:TICKER_FONT_SIZE];
        CGSize textSize = [text sizeWithFont:self.label.font constrainedToSize:textConstrainedSize];
        while (textSize.height > self.frame.size.height && self.label.font.pointSize > TICKER_MINIMUM_FONT_SIZE) {
            self.label.font = [UIFont systemFontOfSize:self.label.font.pointSize-1];
            textSize = [ticker.blurb sizeWithFont:self.label.font constrainedToSize:textConstrainedSize];
        }
        // In cases where the frame is still too large (when we're exceeding minimum font size),
        // use the views size
        if (textSize.height > self.frame.size.height) {
            textSize = [text sizeWithFont:self.label.font constrainedToSize:self.frame.size];
        }

        // Draw 
        self.label.frame = CGRectMake(0, self.frame.size.height/2 - textSize.height/2, self.frame.size.width, textSize.height);
        self.label.text = text;
    }
    [self setNeedsDisplay];
}

希望这对某人有所帮助！