如何缩小行之间的UILabel间距而不剪切标签？

Question

我有一个标签，我试图缩小行之间的间距。我尝试了很多东西，包括改变高度倍数，最小/最大行间距等。当我改变高度倍数时，标签似乎被夹在顶部。我要添加图片作为示例：

This is a regular attributed label with default settings. Constraints: Leading 20, trailing 20, align center to Superview and Align Y to superview

This is the same label but with the height Multiple set at 0.7 which actually shrinks the letter spacing like I want. The issue is that the top of the label is clipped and not adjusted to fit right

有没有人知道如何修复这种缩小行间距但不让标签被剪裁的用途？

提前致谢！

修改

使用Pedro下面的代码，标签行间距会缩小，但现在我的标签文字被剪裁在底部，如下所示：

编辑2：

同样基于Pedros的答案，当我增加defaultLineSpacing = 20时，标签空间非常奇怪。顶部的蓝色部分扩展得更多，而底部仍然像这样被剪掉：

Answer 1

使用以下内容对UILabel进行子类化，并将MINIMUM_SIZE和MAX_SIZE替换为所需的最小字体大小和最大值

class LabelWithAdaptiveTextHeight: UILabel {

override func layoutSubviews() {
    super.layoutSubviews()
    font = fontToFitHeight()
}

private func fontToFitHeight() -> UIFont {

    var minFontSize: CGFloat = MINIMUM_SIZE
    var maxFontSize: CGFloat = MAX_SIZE
    var fontSizeAverage: CGFloat = 0
    var textAndLabelHeightDiff: CGFloat = 0

    while (minFontSize <= maxFontSize) {

        fontSizeAverage = minFontSize + (maxFontSize - minFontSize) / 2

        guard let charsCount = text?.count, charsCount > 0 else {
            break
        }

        if let labelText: String = text {
            let labelHeight = frame.size.height

            let testStringHeight = labelText.size(withAttributes:[NSAttributedStringKey.font: font.withSize(fontSizeAverage)]).height

            textAndLabelHeightDiff = labelHeight - testStringHeight

            if (fontSizeAverage == minFontSize || fontSizeAverage == maxFontSize) {
                if (textAndLabelHeightDiff < 0) {
                    return font.withSize(fontSizeAverage - 1)
                }
                return font.withSize(fontSizeAverage)
            }

            if (textAndLabelHeightDiff < 0) {
                maxFontSize = fontSizeAverage - 1

            } else if (textAndLabelHeightDiff > 0) {
                minFontSize = fontSizeAverage + 1

            } else {
                return font.withSize(fontSizeAverage)
            }
        }
    }
    return font.withSize(fontSizeAverage)
}

}

Answer 2

最快的方法是在标签上添加高度约束。