UILable在Autolayout模式下面自动调节字体大小

一、需求

　　固定UILabel的宽度大小在一定范围，内容能够自动伸缩

二、实施

　　首先加好约束：

　　约束加好之后，需要设置好Autoshrink属性，包括Line break、BaseLine、以及缩小字体所能够达到的最小字体大小。

 　　如果需要在UILabel中添加padding，可以增加以下代码：

@IBDesignable class PaddingLabel: UILabel {

    @IBInspectable var topInset: CGFloat = 5.0
    @IBInspectable var bottomInset: CGFloat = 5.0
    @IBInspectable var leftInset: CGFloat = 7.0
    @IBInspectable var rightInset: CGFloat = 7.0

    override func drawText(in rect: CGRect) {
        let insets = UIEdgeInsets.init(top: topInset, left: leftInset, bottom: bottomInset, right: rightInset)
        super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))
    }

    override var intrinsicContentSize: CGSize {
        let size = super.intrinsicContentSize
        return CGSize(width: size.width + leftInset + rightInset,
                      height: size.height + topInset + bottomInset)
    }    
}

　　https://stackoverflow.com/questions/27459746/adding-space-padding-to-a-uilabel