How to get the screenshot when a view controller is presented over another view controller?

Question

I want to get the screen shot of the current screen.

But whenever MFMailComposeViewController or any other view controller is presented, the screenshot drawn doesnot has a black screen.

//Code to draw what ever is present currently on the screen
- (UIImage*)screenshot {

CGSize imageSize = [[UIScreen mainScreen] bounds].size;


if (NULL != UIGraphicsBeginImageContextWithOptions)
    UIGraphicsBeginImageContextWithOptions(imageSize,YES, 0.0);
else
    UIGraphicsBeginImageContext(imageSize);



CGContextRef context = UIGraphicsGetCurrentContext();

// Iterate over every window from back to front
for (UIWindow *currentWindow in [[UIApplication sharedApplication] windows])
{
    if (![currentWindow respondsToSelector:@selector(screen)] || [currentWindow screen] == [UIScreen mainScreen])
    {



        CGContextSaveGState(context);

        NSLog(@"current alpha %f", currentWindow.alpha);

        CGContextSetAlpha(context, currentWindow.alpha);

        // Center the context around the window's anchor point
        CGContextTranslateCTM(context, [currentWindow center].x, [currentWindow center].y );
        // Apply the window's transform about the anchor point
        CGContextConcatCTM(context, [currentWindow transform]);
        // Offset by the portion of the bounds left of and above the anchor point
        CGContextTranslateCTM(context,
                              -[currentWindow bounds].size.width * [[currentWindow layer] anchorPoint].x,
                              -([currentWindow bounds].size.height ) * [[currentWindow layer] anchorPoint].y );

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

        // Restore the context
        CGContextRestoreGState(context);


    }
}

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

UIGraphicsEndImageContext();

return [image autorelease];}

When the view controller is presented, the for loop in the above code iterate more than once and I get a blank image when mfmailcomposeviewcontroller is presented. though the tab bar controller of the v iew controller below that is visible.

But when i press the cancel button of the mail compser , the action sheet that appears on screen also is not drawn.

Is this due to the opacity in UIGraphicsBeginImageContextWithOptions?

I want to know how to get image of the screen when another view controller is presented.

Is it that default controllers screenshot cannot be obtained?

Please help.

Thanks in advance.

Answer 1

Well you can simply add

ViewOnTop.alpha = 0.0;

to the view which is above the one of which you want to take a screenshot. This will first make the View on top reduce its alpha property to 0 thus making it virtually transparent and then you are taking the screenshot

Add the above code here

- (UIImage*)screenshot {

ViewOnTop.alpha = 0.0;
............
...................
}

EDIT :

For the viewcontroller in the same code add the dismissViewController property to the view that is being presented so that finally the view of which you want the screenshot is visible.