你应该试试这个:

-(CGFloat)dynamicLblHeight:(UILabel *)lbl
{
    CGFloat lblWidth = lbl.frame.size.width;
    CGRect lblTextSize = [lbl.text boundingRectWithSize:CGSizeMake(lblWidth, MAXFLOAT)
                                               options:NSStringDrawingUsesLineFragmentOrigin
                                            attributes:@{NSFontAttributeName:lbl.font}
                                               context:nil];
    return lblTextSize.size.height;
}

UILabel *helpLabel = [[UILabel alloc] init];
NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:label];
helpLabel.attributedText = attrString;
// helpLabel.text = label;

helpLabel.textAlignment = NSTextAlignmentCenter;
helpLabel.lineBreakMode = NSLineBreakByWordWrapping;
helpLabel.numberOfLines = 0;

出于某些原因，它在iOS 6中不为我工作，不知道为什么。尝试了带和不带带属性的文本。任何建议。

这些东西帮助了我

更改UILabel的这些属性

label.numberOfLines = 0;
label.adjustsFontSizeToFitWidth = NO;
label.lineBreakMode = NSLineBreakByWordWrapping;

在输入字符串时使用\n在不同的行中显示不同的单词。

例子:

 NSString *message = @"This \n is \n a demo \n message for \n stackoverflow" ;

当使用NSString填充UILabel时，您可以使用\r转到下一行。

UILabel * label;


label.text = [NSString stringWithFormat:@"%@ \r %@",@"first line",@"seconcd line"];

斯威夫特3 设置行数为零的动态文本信息，这将是有用的变化文本。

var label = UILabel()
let stringValue = "A label\nwith\nmultiline text."
label.text = stringValue
label.numberOfLines = 0
label.lineBreakMode = .byTruncatingTail // or .byWrappingWord
label.minimumScaleFactor = 0.8 . // It is not required but nice to have a minimum scale factor to fit text into label frame

UILabel *textLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 150, 30)];
[textLabel sizeToFit];
textLabel.numberOfLines = 0;
textLabel.text = @"Your String...";