如何制作透明且扁平的 UIBarButtonItem？

Question

我想让我的应用程序的按钮扁平透明，就像 kindle 应用程序中的按钮 (see the shop button)。

我尝试通过代码设置自定义背景，但运气不佳（按钮绘制为矩形，边框颜色填充所有背景）：

- (UIImage *) screenshot {
    // Create a graphics context with the target size
    // On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
    // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
    CGSize imageSize = self.bounds.size;

    if (NULL != UIGraphicsBeginImageContextWithOptions)
        UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    else
        UIGraphicsBeginImageContext(imageSize);

    CGContextRef context = UIGraphicsGetCurrentContext();

    [self.layer renderInContext:context];

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;   
}

+(UIImage *) buttonFlat {
    UIView *bt = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 1.0f, 1.0f)];

    bt.backgroundColor = [UIColor blackColor];
    bt.layer.borderColor = [UIColor lightGrayColor].CGColor;
    bt.layer.borderWidth = 1;
    bt.layer.cornerRadius = 5.0;
    bt.alpha = 0.7;

    return [bt screenshot];
}

我知道如何使用普通的 UIButton，但我更喜欢这样做，以便尽可能保留 UIBarButtonItem 的标准图标...

Answer 1

一个 UIBarButton 可以容纳任何自定义视图：

UIBarButtonItem *barButton = [[UIBarButtonItem alloc] initWithCustomView:someView];