UIButton + XIB子视图=无突出显示

Question

我有一个UIButton，此按钮从xib加载子视图。一切都绘制良好，并且正确调用了委托方法，但是没有突出显示效果。

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

Answer 1

如果所有子视图碰巧都是图像，则有一个疯狂的解决方案：创建多个UIButton作为子视图，并将其高亮/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K-V观察器。这是一个简单的例子：

// 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;
            }
        }
    }
}    

[当我想为具有层，透明度和动态加载内容的UIButton创建一个“图像”时，我必须这样做一次。

Answer 2

您可以将您从xib加载的视图转换为UIImage，然后将该图像添加到UIButton。这样，按下按钮时将显示高亮显示：

UIButton *button;

UIGraphicsBeginImageContext(viewFromXib.frame.size);
[viewFromXib.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[button setImage:image forState:UIControlStateNormal];