iOS UILabel最后一行使用Subclassed insets切断长文本

Question

我一直试图通过使用这个子类方法来获取使用UILabel的插图：

    @IBDesignable class TextLabelWithInsets: UILabel {
    @IBInspectable var topInset: CGFloat = 0.0
    @IBInspectable var leftInset: CGFloat = 0.0
    @IBInspectable var bottomInset: CGFloat = 0.0
    @IBInspectable var rightInset: CGFloat = 0.0

    var insets: UIEdgeInsets {
        get {
            return UIEdgeInsetsMake(topInset, leftInset, bottomInset, rightInset)
        }
        set {
            topInset = newValue.top
            leftInset = newValue.left
            bottomInset = newValue.bottom
            rightInset = newValue.right
        }
    }

    override func drawText(in rect: CGRect) {
        super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))
    }

    override var intrinsicContentSize: CGSize {
        var contentSize = super.intrinsicContentSize
        contentSize.width += leftInset + rightInset
        contentSize.height += topInset + bottomInset
        print("Content Size: " + String(describing: contentSize))
        return contentSize
    }
}

问题是这只适用于较小的文本块。似乎只要文本足够长，最后一行就会被切断。

任何想法如何解决这个问题？在高度上添加额外的像素会起作用，但会使较小的像素看起来很笨我不知道这里的问题是什么，代码在我脑海中是有意义的。

以下是其他有用的情况：

func commonInit() {
    oppositeSideEdgeSpacing = screen.size.width/4

    textLabel = TextLabelWithInsets(frame: .zero)
    textLabel.layer.cornerRadius = bubbleCornerRadius
    textLabel.clipsToBounds = true

    textLabel.topInset = bubbleTopInsetSpacing
    textLabel.bottomInset = bubbleBottomInsetSpacing
    textLabel.leftInset = bubbleLeftInsetSpacing
    textLabel.rightInset = bubbleRightInsetSpacing

    textLabel.numberOfLines = 0
    textLabel.translatesAutoresizingMaskIntoConstraints = false
    textLabel.textAlignment = .left
    textLabel.backgroundColor = UIColor(hexString: "CDDCE0") // TODO: Fix this

    addSubview(textLabel)

    if !isMessageFromCurrentUser {
        textLabel.topAnchor.constraint(equalTo: topAnchor, constant: bubbleEdgeSpacing).set(active: true)
        textLabel.leftAnchor.constraint(equalTo: leftAnchor, constant: bubbleEdgeSpacing).set(active: true)
        textLabel.rightAnchor.constraint(equalTo: rightAnchor, constant: -oppositeSideEdgeSpacing).set(active: true)
        textLabel.bottomAnchor.constraint(equalTo: bottomAnchor).set(active: true)
    }
}