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
        }
    }
}

我想在这个答案中加入一些新的东西，这样我就不会感觉那么糟糕了……以下是斯威夫特的回答:

import Cocoa

let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = 40

let attrString = NSMutableAttributedString(string: "Swift Answer")
attrString.addAttribute(.paragraphStyle, value:paragraphStyle, range:NSMakeRange(0, attrString.length))

var tableViewCell = NSTableCellView()
tableViewCell.textField.attributedStringValue = attrString

简单的回答是:你不能。要改变文本行间的间距，你必须继承UILabel并滚动自己的drawTextInRect，或者创建多个标签。”

参见:设置UILabel行间距

这是一个非常老的答案，其他人已经添加了新的更好的方法来处理这个问题。请参阅下面提供的最新答案。

下面是UILabel的一个子类，它设置lineHeightMultiple并确保内在高度足够大，不会截断文本。

@IBDesignable
class Label: UILabel {
    override var intrinsicContentSize: CGSize {
        var size = super.intrinsicContentSize
        let padding = (1.0 - lineHeightMultiple) * font.pointSize
        size.height += padding
        return size
    }

    override var text: String? {
        didSet {
            updateAttributedText()
        }
    }

    @IBInspectable var lineHeightMultiple: CGFloat = 1.0 {
        didSet {
            updateAttributedText()
        }
    }

    private func updateAttributedText() {
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineHeightMultiple = lineHeightMultiple
        attributedText = NSAttributedString(string: text ?? "", attributes: [
            .font: font,
            .paragraphStyle: paragraphStyle,
            .foregroundColor: textColor
        ])
        invalidateIntrinsicContentSize()
    }
}

这里提到的解决方案对我不起作用。我发现了一个稍微不同的方式来做它与iOS 6 NSAttributeString:

myLabel.numberOfLines = 0; 
NSString* string = @"String with line one. \n Line two. \n Line three.";
NSMutableParagraphStyle *style  = [[NSMutableParagraphStyle alloc] init];
style.minimumLineHeight = 30.f;
style.maximumLineHeight = 30.f;
NSDictionary *attributtes = @{NSParagraphStyleAttributeName : style,};
myLabel.attributedText = [[NSAttributedString alloc] initWithString:string
                                                         attributes:attributtes];   
[myLabel sizeToFit];

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;

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
    }
}