捕捉QLPreviewController的屏幕在iOS 6中引起问题

Question

在站点上，他们发布了用于屏幕捕捉的代码。所有操作都正常，只是它不捕获使用QLPreviewController在iOS 6下预览的文件。

我想知道他们是否正在使用一些新的OpenGL ES来呈现文件预览，使其无法捕获？理论上，这段代码应该能够捕获屏幕上的任何内容，对吗？？

来自index.html

- (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 = [[UIScreen mainScreen] bounds].size;
if (NULL != UIGraphicsBeginImageContextWithOptions)
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
else
    UIGraphicsBeginImageContext(imageSize);

CGContextRef context = UIGraphicsGetCurrentContext();

// Iterate over every window from back to front
for (UIWindow *window in [[UIApplication sharedApplication] windows]) 
{
    if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen])
    {
        // -renderInContext: renders in the coordinate space of the layer,
        // so we must first apply the layer's geometry to the graphics context
        CGContextSaveGState(context);
        // Center the context around the window's anchor point
        CGContextTranslateCTM(context, [window center].x, [window center].y);
        // Apply the window's transform about the anchor point
        CGContextConcatCTM(context, [window transform]);
        // Offset by the portion of the bounds left of and above the anchor point
        CGContextTranslateCTM(context,
                              -[window bounds].size.width * [[window layer] anchorPoint].x,
                              -[window bounds].size.height * [[window layer] anchorPoint].y);

        // Render the layer hierarchy to the current context
        [[window layer] renderInContext:context];

        // Restore the context
        CGContextRestoreGState(context);
    }
}

// Retrieve the screenshot image
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return image;
}

Answer 1

这听起来不太相似，但实际上不起作用的原因与它不起作用的原因相同：iOS 6 UIGestures (Tap) stops working with QLPreviewController

因为ios 6，QLPreviewController实际上是一个完全独立的应用程序(分离的进程和一切)

因此，当您按下=>时，整个应用程序都会移动到bg，包括它的窗口。

=> QlController从来都不是你的窗口的一部分