Swift 4标签扩展。在传入函数之前创建NSMutableAttributedString，以防有属性文本需要额外的属性。

extension UILabel {

    func setLineHeightMultiple(to height: CGFloat, withAttributedText attributedText: NSMutableAttributedString) {

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineSpacing = 1.0
        paragraphStyle.lineHeightMultiple = height
        paragraphStyle.alignment = textAlignment

        attributedText.addAttribute(.paragraphStyle, value: paragraphStyle, range: NSRange(location: 0, length: attributedText.length - 1))

        self.attributedText = attributedText
    }
}

这段代码适用于我(ios 7和ios 8肯定是如此)。

_label.numberOfLines=2;
_label.textColor=[UIColor whiteColor];

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.lineHeightMultiple=0.5;
paragraphStyle.alignment = NSTextAlignmentCenter;
paragraphStyle.lineSpacing = 1.0;

NSDictionary *nameAttributes=@{
                               NSParagraphStyleAttributeName : paragraphStyle,
                               NSBaselineOffsetAttributeName:@2.0
                               };


NSAttributedString *string=[[NSAttributedString alloc] initWithString:@"22m\nago" attributes:nameAttributes];
_label.attributedText=string;

从ios6开始，你可以为UILabel设置带属性字符串。检查以下内容:

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:label.text];
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.lineSpacing = spacing;
[attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, label.text.length)];

label.attributedText = attributedString;

另一个答案……如果你通过编程的方式传递字符串，你需要传递一个带属性的字符串，而不是一个普通的字符串，并改变它的风格。

NSMutableAttributedString * attrString = [[NSMutableAttributedString alloc] initWithString:@"Your \nregular \nstring"];
NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
[style setLineSpacing:4];
[attrString addAttribute:NSParagraphStyleAttributeName
                   value:style
                   range:NSMakeRange(0, attrString.length)];
_label.attributedText = attrString;

根据@Mike的回答，减少lineHeightMultiple是关键点。下面的例子，它很适合我:

NSString* text = label.text;
CGFloat textWidth = [text sizeWithAttributes:@{NSFontAttributeName: label.font}].width;
if (textWidth > label.frame.size.width) {
  NSMutableParagraphStyle *paragraph = [[NSMutableParagraphStyle alloc] init];
  paragraph.alignment = NSTextAlignmentCenter;
  paragraph.lineSpacing = 1.0f;
  paragraph.lineHeightMultiple = 0.75;     // Reduce this value !!!
  NSMutableAttributedString* attrText = [[NSMutableAttributedString alloc] initWithString:text];
  [attrText addAttribute:NSParagraphStyleAttributeName value:paragraph range:NSMakeRange(0, text.length)];
  label.attributedText = attrText;
}

这是我在swift中的解决方案。子类应该同时适用于attributedText和text属性以及characterSpacing + lineSpacing。如果设置了新字符串或attributedString，则保留空格。

open class UHBCustomLabel : UILabel {
    @IBInspectable open var characterSpacing:CGFloat = 1 {
        didSet {
            updateWithSpacing()
        }

    }
    @IBInspectable open var lines_spacing:CGFloat = -1 {
        didSet {
            updateWithSpacing()
        }

    }
    open override var text: String? {
        set {
            super.text = newValue
            updateWithSpacing()
        }
        get {
            return super.text
        }
    }
    open override var attributedText: NSAttributedString? {
        set {
            super.attributedText = newValue
            updateWithSpacing() 
        }
        get {
            return super.attributedText
        }
    }
    func updateWithSpacing() {
        let attributedString = self.attributedText == nil ? NSMutableAttributedString(string: self.text ?? "") : NSMutableAttributedString(attributedString: attributedText!)
        attributedString.addAttribute(NSKernAttributeName, value: self.characterSpacing, range: NSRange(location: 0, length: attributedString.length))
        if lines_spacing >= 0 {
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.lineSpacing = lines_spacing
            paragraphStyle.alignment = textAlignment
            attributedString.addAttribute(NSParagraphStyleAttributeName, value:paragraphStyle, range:NSMakeRange(0, attributedString.length))
        }
        super.attributedText = attributedString
    }
}