自定义清除按钮

Question

我想在UITextField上创建自定义清除按钮,即使用rightView并将图像放在那里,问题是将原始清除按钮事件附加到该自定义rightView.

在Objective-C中,我可以这样做:

SEL clearButtonSelector = NSSelectorFromString(@"clearButton");
// Reference clearButton getter
IMP clearButtonImplementation = [self methodForSelector:clearButtonSelector];
// Create function pointer that returns UIButton from implementation of method that contains clearButtonSelector
UIButton * (* clearButtonFunctionPointer)(id, SEL) = (void *)clearButtonImplementation;
// Set clearTextFieldButton reference to “clearButton” from clearButtonSelector
UIButton *_clearTextFieldButton = clearButtonFunctionPointer(self, clearButtonSelector);
[_clearTextFieldButton setImage:[UIImage imageNamed:@"icon_remove"] forState:UIControlStateNormal];
self.hasClearButtonAsRightView = YES;

现在如何将此转换为Swift？或任何解决方法的想法？

Answer 1

您可以添加自定义按钮作为UITextField此类的右视图

class CustomTextField : UITextField
{
    override init(frame: CGRect) {
        super.init(frame: frame)

        let clearButton = UIButton(frame: CGRect(origin: .zero, size: CGSize(width: 15, height: 15))
        clearButton.setImage(UIImage(named: "clear.png")!, forState: UIControlState.Normal)

        self.rightView = clearButton
        clearButton.addTarget(self, action: "clearClicked:", forControlEvents: .touchUpInside)

        self.clearButtonMode = .never
        self.rightViewMode = .always
    }

    func clearClicked(sender: UIButton)
    {
        self.text = ""
    }

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
}

Answer 2

按照其他答案中的建议实现自定义文本字段不是一个好主意.如果可能的话,您应该尝试使用扩展而不是继承,因为继承您更有可能需要对代码库进行重大更改以响应更改,而使用扩展您可以更灵活地进行更改.

我强烈建议您不要实现自定义文本字段,而是扩展UITextField类,如下所示:

extension UITextField {
    func applyCustomClearButton() {
        clearButtonMode = .Never
        rightViewMode   = .WhileEditing

        let clearButton = UIButton(frame: CGRectMake(0, 0, 16, 16))
        clearButton.setImage(UIImage(name: "iCFieldClear")!, forState: .Normal)
        clearButton.addTarget(self, action: "clearClicked:", forControlEvents: .TouchUpInside)

        rightView = clearButton
    }

    func clearClicked(sender:UIButton) {
        text = ""
    }
}

然后使用它你只需这样做:

yourTextField.applyCustomClearButton()