UIButton + XIB subview = 无突出显示

Question

我有一个 UIButton，此按钮从 xib 加载 subview 。一切都绘制得很好，委托(delegate)方法调用正确，但没有高亮效果。

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

Answer 1

如果您的所有 subview 恰好都是图像，那么有一个疯狂的解决方案:创建多个 UIButton 作为 subview 并将它们的突出显示/禁用状态绑定(bind)在一起。将它们全部添加为主按钮的 subview ，禁用用户交互，并在主按钮上使用 K-V 观察器。这是一个简单的示例:

// 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;
            }
        }
    }
}    

当我想要为 UIButton 提供一个具有图层、透明度和动态加载内容的“图像”时，我必须这样做一次。