在Swift 2.0中…

添加一个扩展:

extension UIView {
    func attributesWithLineHeight(font: String, color: UIColor, fontSize: CGFloat, kern: Double, lineHeightMultiple: CGFloat) -> [String: NSObject] {
        let titleParagraphStyle = NSMutableParagraphStyle()
        titleParagraphStyle.lineHeightMultiple = lineHeightMultiple

        let attribute = [
            NSForegroundColorAttributeName: color,
            NSKernAttributeName: kern,
            NSFontAttributeName : UIFont(name: font, size: fontSize)!,
            NSParagraphStyleAttributeName: titleParagraphStyle
        ]
        return attribute
    }
}

现在，设置你的UILabel为attributedText:

self.label.attributedText = NSMutableAttributedString(string: "SwiftExample", attributes: attributesWithLineHeight("SourceSans-Regular", color: UIColor.whiteColor(), fontSize: 20, kern: 2.0, lineHeightMultiple: 0.5))    

显然，我添加了一堆您可能不需要的参数。玩周围-随时重写方法-我正在寻找这个在一堆不同的答案，所以我想我会张贴整个扩展，以防它帮助某人在那里…rab

SWIFT 3有用的扩展设置行间的空间更容易:)

extension UILabel
{
    func setLineHeight(lineHeight: CGFloat)
    {
        let text = self.text
        if let text = text 
        {

            let attributeString = NSMutableAttributedString(string: text)
            let style = NSMutableParagraphStyle()

           style.lineSpacing = lineHeight
           attributeString.addAttribute(NSParagraphStyleAttributeName,
                                        value: style,
                                        range: NSMakeRange(0, text.characters.count))

           self.attributedText = attributeString
        }
    }
}

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;
}

我找到了一种方法，你可以设置真实的行高(不是一个因素)，它甚至在界面生成器中渲染。按照下面的说明做就可以了。代码是用Swift 4编写的。

步骤#1:创建一个名为DesignableLabel.swift的文件，并插入以下代码:

import UIKit

@IBDesignable
class DesignableLabel: UILabel {
    @IBInspectable var lineHeight: CGFloat = 20 {
        didSet {
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.minimumLineHeight = lineHeight
            paragraphStyle.maximumLineHeight = lineHeight
            paragraphStyle.alignment = self.textAlignment

            let attrString = NSMutableAttributedString(string: text!)
            attrString.addAttribute(NSAttributedStringKey.font, value: font, range: NSRange(location: 0, length: attrString.length))
            attrString.addAttribute(NSAttributedStringKey.paragraphStyle, value: paragraphStyle, range: NSRange(location: 0, length: attrString.length))
            attributedText = attrString
        }
    }
}

步骤#2:将UILabel放入Storyboard/XIB中，并将其类设置为DesignableLabel。等待项目构建完成(构建必须成功!)。

步骤3:现在你应该在属性窗格中看到一个名为“Line Height”的新属性。只需设置您喜欢的值，您应该立即看到结果!

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
    }
}

在Swift中，作为一个函数，灵感来自DarkDust

// Usage: setTextWithLineSpacing(myEpicUILabel,text:"Hello",lineSpacing:20)
func setTextWithLineSpacing(label:UILabel,text:String,lineSpacing:CGFloat)
{
    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.lineSpacing = lineSpacing

    let attrString = NSMutableAttributedString(string: text)
    attrString.addAttribute(NSAttributedString.Key.paragraphStyle, value:paragraphStyle, range:NSMakeRange(0, attrString.length))

    label.attributedText = attrString
}