如何修复在iOS 7中显示为黑色的半透明工具栏截图？

Question

我的顶部和底部工具栏在应用程序中显示为黑色，显示为浅灰色。我假设它可能与我在工具栏的.storyboard属性检查器中找到的默认“半透明复选框”有关吗？

我正在使用UIActivityViewController在电子邮件中拍摄此图像。这是获取屏幕截图的代码：

// Grab a screenshot
UIGraphicsBeginImageContext(self.view.bounds.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *imageToShare = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Answer 1

此处找到解决方案：iOS: what's the fastest, most performant way to make a screenshot programmatically?

这似乎应该是Apple框架提供的工厂方法。我把它作为Utils.h / .m类：

+ (UIImage *)screenshot
{
    CGSize imageSize = CGSizeZero;

    UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
    if (UIInterfaceOrientationIsPortrait(orientation)) {
        imageSize = [UIScreen mainScreen].bounds.size;
    } else {
        imageSize = CGSizeMake([UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width);
    }

    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();
    for (UIWindow *window in [[UIApplication sharedApplication] windows]) {
        CGContextSaveGState(context);
        CGContextTranslateCTM(context, window.center.x, window.center.y);
        CGContextConcatCTM(context, window.transform);
        CGContextTranslateCTM(context, -window.bounds.size.width * window.layer.anchorPoint.x, -window.bounds.size.height * window.layer.anchorPoint.y);
        if (orientation == UIInterfaceOrientationLandscapeLeft) {
            CGContextRotateCTM(context, M_PI_2);
            CGContextTranslateCTM(context, 0, -imageSize.width);
        } else if (orientation == UIInterfaceOrientationLandscapeRight) {
            CGContextRotateCTM(context, -M_PI_2);
            CGContextTranslateCTM(context, -imageSize.height, 0);
        } else if (orientation == UIInterfaceOrientationPortraitUpsideDown) {
            CGContextRotateCTM(context, M_PI);
            CGContextTranslateCTM(context, -imageSize.width, -imageSize.height);
        }
        if ([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)]) {
            [window drawViewHierarchyInRect:window.bounds afterScreenUpdates:YES];
        } else {
            [window.layer renderInContext:context];
        }
        CGContextRestoreGState(context);
    }

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

Answer 2

您应该在渲染之前设置图层上的颜色：

self.view.backgroundColor = [UIColor whateverColorYouWant];
UIGraphicsBeginImageContext(self.view.bounds.size); 
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()]; 
UIImage *imageToShare = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

看看that anwser