带有 UIMenucontroller 的 UILabel 不会放弃触摸外部的第一响应者

Question

我对 UILabel 进行了子类化以提供复制菜单，并希望添加某种类型的效果，使 UILabel 在显示此菜单时脱颖而出。

现在我正在尝试添加和删除边框。它工作正常，但是如果用户触摸标签，然后触摸标签外部，则边框不会消失，尽管复制菜单会消失。

添加一些 NSLog 后，发生这种情况时似乎没有调用 resignfirstresponder 。当这种情况发生时，响应者链中会发生什么？我怎样才能让边框在这种情况下消失？

代码如下：

@implementation CopyLabel

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    if(action == @selector(copy:)) {
        return YES;
    }
    else {
        return [super canPerformAction:action withSender:sender];
    }
}

- (BOOL) canBecomeFirstResponder {
    return YES;
}

- (BOOL)becomeFirstResponder {
    if([super becomeFirstResponder]) {
        self.highlighted = YES; 

        UIMenuController *menu = [UIMenuController sharedMenuController];
        [menu setTargetRect:self.bounds inView:self];
        [menu setMenuVisible:YES animated:YES];

        return YES;
    }
    return NO;
}

- (BOOL)resignFirstResponder {
    if([super resignFirstResponder]) {
        self.highlighted = NO; 

        UIMenuController *menu = [UIMenuController sharedMenuController];
        [menu setMenuVisible:NO animated:YES];
        [menu update];

        NSLog(@"Resign");
        return true;
    }
    return false;
}


- (void)copy:(id)sender {
    UIPasteboard *board = [UIPasteboard generalPasteboard];
    [board setString:self.text];
    self.highlighted = NO;
    [self resignFirstResponder];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    if([self isFirstResponder]) {
        [self resignFirstResponder];
    }
    else if([self becomeFirstResponder]) {

    } else {
        [self resignFirstResponder];
    }
}

- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];
    self.layer.borderColor = [UIColor blueColor].CGColor;
    self.layer.borderWidth = 0.0;
    if(self.highlighted) {
        self.layer.borderWidth = 1.0;
    }
}


@end

Answer 1

UIMenuController 发布 UIMenuControllerDidHideMenuNotification。当您监听该通知（使用 NSNotificationCenter）时，您可以在正确的时间将 resignFirstResponder 发送到您的标签。

例子：

- (id)init... {
    ...
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(editMenuHidden)
                                                 name:UIMenuControllerDidHideMenuNotification 
                                               object:nil];
    ...
}

- (void)dealloc {
    ...
    [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                name:UIMenuControllerDidHideMenuNotification 
                                              object:nil];
    ...
}

- (void)editMenuHidden {
    [self resignFirstResponder];
}

...