touch取消textfield的第一响应

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    
    for touch:AnyObject in touches {
        let t:UITouch = touch as! UITouch
        //检测当前触摸的view是否是textField
        if t.view == pwdField || t.view == pwdField || t.view == phoneField{
            t.view?.becomeFirstResponder()
        }else{
            phoneField.resignFirstResponder()
            pwdField.resignFirstResponder()
            verificationField.resignFirstResponder()
            self.resignFirstResponder()
        }
    }
    
}