Swift 修改UITextField编辑时清除按钮的样式

项目有皮肤切换，UITextField的清除按钮在暗环境下几乎看不到，所以要更改样式，更换图片

class EXAssetTextField: UITextField {

    // CYC666
    override func layoutSubviews() {
        super.layoutSubviews()
        
        
        self.changeClearButtonImage()
        
    }
    
    // MARK: 修改清除按钮图片
    @objc func changeClearButtonImage() {
        
        if let temp = self.value(forKey: "_clearButton") {
            
            let btn = temp as! UIButton
            btn.setImage(CTools.getImage("EXAssets49"), for: .normal)  // 此处自行修改图片

        } else {
            
            var btn: UIButton?
            for item in self.subviews {
                
                if item is UIButton {
                    btn = item as! UIButton
                    break
                }
            }
            
            if btn != nil {
                btn?.setImage(CTools.getImage("EXAssets49"), for: .normal)  // 此处自行修改图片
            }
        }
        
    }

}