我也在研究这个特定的问题，所以我采纳了D.S.和nevan king的想法，并将它们基本上组合成一个子类，该子类实现了垂直对齐属性，这也允许您不止一次地更改对齐。它借用了UIControlContentVerticalAlignment类型，还支持UIControlContent垂直对齐填充。

从我所看到的情况来看，numberOfLines在垂直对齐方面似乎毫无用处，因此在这个子类中，当应用垂直对齐时，它总是设置为0。此外，如果您需要多行文本标签，您仍然需要自己设置lineBreakMode。

这就是：GitHub上的QALabel

（截至2018年3月7日）

斯威夫特4

let maxFrameHeight = 75

myLabel = UILabel()
myLabel.frame = CGRect(x: 9, y: 9, width: 126, height: maxFrameHeight)
myLabel.text = "my labels text displayed"
myLabel.numberOfLines = 0

myLabel.sizeToFit()
let newFrameHeight = myLabel.frame.size.height
let safeNewHeight = min(newFrameHeight, maxFrameHeight)

myLabel.frame = CGRect(x: 9, y: 9, width: 126, height: safeNewHeight)

这将获得所需的结果，并确保UILabel的新高度不会超过您希望的该标签的特定最大高度。

如果可以选择创建自己的自定义视图，可以执行以下操作：

- (void)drawRect:(CGRect)rect
{
    CGRect bounds = self.bounds;
    [self.textColor set];
    [self.text drawInRect:bounds
                 withFont:self.font
            lineBreakMode:UILineBreakModeTailTruncation
                alignment:self.textAlignment];
}

Swift 2.0版本：

在空Swift文件中生成常量枚举值。

//  AppRef.swift

import UIKit
import Foundation

enum UILabelTextPositions : String {

 case VERTICAL_ALIGNMENT_TOP = "VerticalAlignmentTop"
 case VERTICAL_ALIGNMENT_MIDDLE = "VerticalAlignmentMiddle"
 case VERTICAL_ALIGNMENT_BOTTOM = "VerticalAlignmentBottom"

}

使用UILabel扩展：

创建一个空的Swift类并命名它

//  AppExtensions.swift

import Foundation
import UIKit

extension UILabel{ 
 func makeLabelTextPosition (sampleLabel :UILabel?, positionIdentifier : String) -> UILabel
 {
  let rect = sampleLabel!.textRectForBounds(bounds, limitedToNumberOfLines: 0)

  switch positionIdentifier
  {
  case "VerticalAlignmentTop":
   sampleLabel!.frame = CGRectMake(bounds.origin.x+5, bounds.origin.y, rect.size.width, rect.size.height)
   break;

  case "VerticalAlignmentMiddle":
   sampleLabel!.frame = CGRectMake(bounds.origin.x+5,bounds.origin.y + (bounds.size.height - rect.size.height) / 2,
    rect.size.width, rect.size.height);
   break;

  case "VerticalAlignmentBottom":
   sampleLabel!.frame = CGRectMake(bounds.origin.x+5, bounds.origin.y + (bounds.size.height - rect.size.height),rect.size.width, rect.size.height);
   break;

  default:
   sampleLabel!.frame = bounds;
   break;
  }
  return sampleLabel!

 }
}

用法：

myMessageLabel.makeLabelTextPosition(messageLabel, positionIdentifier: UILabelTextPositions.VERTICAL_ALIGNMENT_TOP.rawValue)

我重复了戴莱辛的建议，并添加了一个UIEdgeInset，以允许调整边距。周围环境不错。

- (id)init
{
    if (self = [super init]) {
        contentEdgeInsets = UIEdgeInsetsZero;
    }

    return self;
}

- (void)layoutSubviews
{
    CGRect localBounds = self.bounds;
    localBounds = CGRectMake(MAX(0, localBounds.origin.x + contentEdgeInsets.left), 
                             MAX(0, localBounds.origin.y + contentEdgeInsets.top), 
                             MIN(localBounds.size.width, localBounds.size.width - (contentEdgeInsets.left + contentEdgeInsets.right)), 
                             MIN(localBounds.size.height, localBounds.size.height - (contentEdgeInsets.top + contentEdgeInsets.bottom)));

    for (UIView *subview in self.subviews) {
        if ([subview isKindOfClass:[UILabel class]]) {
            UILabel *label = (UILabel*)subview;
            CGSize lineSize = [label.text sizeWithFont:label.font];
            CGSize sizeForText = [label.text sizeWithFont:label.font constrainedToSize:localBounds.size lineBreakMode:label.lineBreakMode];

            NSInteger numberOfLines = ceilf(sizeForText.height/lineSize.height);

            label.numberOfLines = numberOfLines;
            label.frame = CGRectMake(MAX(0, contentEdgeInsets.left), MAX(0, contentEdgeInsets.top), localBounds.size.width, MIN(localBounds.size.height, lineSize.height * numberOfLines)); 
        }
    }
}

试试这个！！太手动了，但对我来说很完美。

[labelName setText:@"This is just a demo"];

NSMutableString *yourString1= @"This is just a demo";


// breaking string
labelName.lineBreakMode=UILineBreakModeTailTruncation;
labelName.numberOfLines = 3;


CGSize maximumLabelSize1 = CGSizeMake(276,37); // Your Maximum text size

CGSize expectedLabelSize1 = [yourString1 sizeWithFont:labelName.font
                                    constrainedToSize:maximumLabelSize1
                                        lineBreakMode:labelName.lineBreakMode];

[labelName setText:yourString1];


CGRect newFrame1 = labelName.frame;
if (expectedLabelSize1.height>=10)
{
    newFrame1.size.height = expectedLabelSize1.height;
}

labelName.frame = newFrame1;