UIButton + XIB 子视图 = 没有高亮

Question

我有一个 UIButton，这个按钮从 xib 加载一个子视图。一切都画得很好，并且正确调用了委托方法，但没有高亮效果。

我将 xib 上的所有内容都设置为 userInteractionEnabled=false。如果我删除这些子视图，突出显示效果会再次起作用。

Answer 1

如果你所有的子视图碰巧都是图像，有一个疯狂的解决方案：创建多个 UIButton 作为子视图并将它们的高亮/禁用状态绑定在一起。将它们全部添加为主按钮的子视图，禁用用户交互，并在主按钮上使用 KV 观察器。这是一个快速示例：

// Only perform the addObserver part if from a XIB
- (UIButton *) makeMasterButton { 
    // Create some buttons
    UIButton *masterButton = [UIButton buttonWithType:UIButtonTypeCustom];
    masterButtonFrame = CGRectMake(0,0,100,100);

    UIButton *slaveButton1 = [UIButton buttonWithType:UIButtonTypeCustom];
    slaveButton1.userInteractionEnabled = NO;
    [slaveButton1 setImage:[UIImage imageNamed:@"Top.png"]];
    slaveButton1.frame = CGRectMake(0, 0,100,50);
    [masterButton addSubview:slaveButton1];

    UIButton *slaveButton2 = [UIButton buttonWithType:UIButtonTypeCustom];
    slaveButton2.userInteractionEnabled = NO;
    [slaveButton2 setImage:[UIImage imageNamed:@"Bottom.png"]];
    slaveButton2.frame = CGRectMake(0,50,100,50);
    [masterButton addSubview:slaveButton2];

    // Secret sauce: add a K-V observer
    [masterButton addObserver:self forKeyPath:@"highlighted" options:(NSKeyValueObservingOptionNew) context:NULL];
    [masterButton addObserver:self forKeyPath:@"enabled" options:(NSKeyValueObservingOptionNew) context:NULL];
    return masterButton;
}

 ...

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([object isKindOfClass:[UIButton class]]) {
        UIButton *button = (UIButton *)object;
        for (id subview in button.subviews) {
            if ([subview isKindOfClass:[UIButton class]]) {
                UIButton *buttonSubview = (UIButton *) subview;
                buttonSubview.highlighted = button.highlighted;
                buttonSubview.enabled = button.enabled;
            }
        }
    }
}    

当我想为具有图层、透明度和动态加载内容的 UIButton 制作“图像”时，我不得不这样做一次。