Snapshotting on iOS

UIImage+Snapshot.m

+ (UIImage *)snapshotView:(UIView *)view {
    UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, [[UIScreen mainScreen] scale]); //0
    [view drawViewHierarchyInRect:view.frame afterScreenUpdates:YES];
    UIImage *snapshot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return snapshot;
}

+ (UIImage *)snapshot {
    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, [[UIScreen mainScreen] scale]);
    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;
}