You can get the screen shot of the screen by calling -renderInContext method of CALayer on your top view like this.
UIGraphicsBeginImageContext(self.view.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[self.view.layer renderInContext:context];
UIImage *imgScreenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
here, imgScreenShot is the desired image. enjoy programming!