【Swift】UILabel 设置内边距

class UILabelPadding : UILabel {
    
    private var padding = UIEdgeInsetsZero
    
    @IBInspectable
    var paddingLeft: CGFloat {
        get { return padding.left }
        set { padding.left = newValue }
    }
    
    @IBInspectable
    var paddingRight: CGFloat {
        get { return padding.right }
        set { padding.right = newValue }
    }
    
    @IBInspectable
    var paddingTop: CGFloat {
        get { return padding.top }
        set { padding.top = newValue }
    }
    
    @IBInspectable
    var paddingBottom: CGFloat {
        get { return padding.bottom }
        set { padding.bottom = newValue }
    }
    
    override func drawTextInRect(rect: CGRect) {
        super.drawTextInRect(UIEdgeInsetsInsetRect(rect, padding))
    }

    override func textRectForBounds(bounds: CGRect, limitedToNumberOfLines numberOfLines: Int) -> CGRect {
        let insets = self.padding
        var rect = super.textRectForBounds(UIEdgeInsetsInsetRect(bounds, insets), limitedToNumberOfLines: numberOfLines)
        rect.origin.x    -= insets.left
        rect.origin.y    -= insets.top
        rect.size.width  += (insets.left + insets.right)
        rect.size.height += (insets.top + insets.bottom)
        return rect
    }

}