UIlabel- 根据内容设置label高度

extension UILabel{
    func requiredHeight() -> CGFloat {
        let frame = CGRect(x: 0, y: 0, width: labelWidth, height: CGFloat.greatestFiniteMagnitude)
        let label = UILabel(frame: frame)
        label.numberOfLines = 0
        label.lineBreakMode = NSLineBreakMode.byWordWrapping
        label.font = self.font
        label.text = self.text
        
        label.sizeToFit()
        
        return label.frame.height
    }
}

说明: labelWidth是需要你定的label宽度