macos - NSResponder resignFirstResponder 在错误的对象上触发

Question

我有一个带有一些 NSTextField 的 Mac 应用程序(SDK 10.10):

由于我需要在文本字段获得和放弃焦点时收到通知，因此我对 NSTextField 进行了子类化:

@interface MyTextField : NSTextField
@end

@implementation MyTextField

- (BOOL)becomeFirstResponder
{
    BOOL didBecomeFirstResponder = [super becomeFirstResponder];
    NSLog(@"%@ didBecomeFirstResponder = %@", [self accessibilityLabel], didBecomeFirstResponder?@"YES":@"NO");
    return didBecomeFirstResponder;
}

- (BOOL)resignFirstResponder
{
    BOOL didResignFirstResponder = [super resignFirstResponder];
    NSLog(@"%@ didResignFirstResponder = %@", [self accessibilityLabel], didResignFirstResponder?@"YES":@"NO");
    return didResignFirstResponder;
}

@end

当运行此代码并在 3 个文本字段之间切换时，我在控制台中得到以下输出:

firstField didResignFirstResponder = YES
firstField didBecomeFirstResponder = YES
secondField didResignFirstResponder = YES
secondField didBecomeFirstResponder = YES
thirdField didResignFirstResponder = YES
thirdField didBecomeFirstResponder = YES
firstField didResignFirstResponder = YES
firstField didBecomeFirstResponder = YES
secondField didResignFirstResponder = YES
secondField didBecomeFirstResponder = YES

每次我按 TAB 键(或单击非事件文本字段之一)时，应用程序都会输出

<new first responder> didResignFirstResponder = YES
<new first responder> didBecomeFirstResponder = YES

难道不是

<old first responder> didResignFirstResponder = YES
<new first responder> didBecomeFirstResponder = YES

？？？

我这里有什么严重错误吗？

- (BOOL)resignFirstResponder 的文档说

Notifies the receiver that it’s been asked to relinquish its status as first responder in its window.

那么为什么要在新的第一响应者而不是旧的第一响应者上调用 resignFirstResponder 呢？

Answer 1

我遇到了同样的问题，但找不到解决方案，因此我最终解决了这个问题并使用 textDidEndEditing() 方法来达到相同的目的。快速代码:

MyTextField 是 NSTextField 的子类，并向其中添加 myDelegate 属性，该属性应在文本字段失去焦点后处理逻辑。

class MyTextField : NSTextField
{

/// Custom delegate with other methods than NSTextFieldDelegate.
var myDelegate: MyTextFieldDelegate? = nil;

override func becomeFirstResponder() -> Bool {
    let became = super.becomeFirstResponder();
    if (became) {
        self.myDelegate?.myTextFieldDidBecomeFirstResponder(self);
    }
    return became;
}

override func resignFirstResponder() -> Bool {
    let resigned = super.resignFirstResponder();
    if (resigned) {
        self.myDelegate?.myTextFieldDidResignFirstResponder(self);
    }
    return resigned;
}

override func textDidEndEditing(obj: NSNotification) {
    super.textDidEndEditing(obj);
    self.myDelegate?.myTextFieldDidResignFirstResponder(self);
}

}

协议(protocol)本身:

protocol MyTextFieldDelegate
{

    func myTextFieldDidBecomeFirstResponder(textField: MyTextField);

    func myTextFieldDidResignFirstResponder(textField: MyTextField);
}

显然，您可以直接实现失去/获得焦点逻辑(例如绘制不同的边框等)，而不是使用和调用委托(delegate)。

线索是 textDidEndEditing() 方法，当我单击另一个字段、按 Enter 或按 Tab 键退出时，它似乎工作得很好。