Mask problem with renderInContext of CALayer

[hk007]

When using renderInContext method of CALayer the mask layers are not rendered. The result looks ugly, the entire track image is show in the UIImage.
I know the real problem is that renderInContext does not support mask layer -- but is there something that can be done in TTSwitch to address this? My app requires screenshot of UIView which contains the Switch. I just finished replacing all the Swtiches in the app with TTSwitch... would hate to revert back to UISwitch.

Test code to reproduce the issue (modified the example project):

#import <UIKit/UIKit.h>
#import <MessageUI/MessageUI.h>
#import <MessageUI/MFMailComposeViewController.h>

@interface TTXibViewController : UIViewController <MFMailComposeViewControllerDelegate>

@end





#import "TTXibViewController.h"
#import "TTSwitch.h"
#import <QuartzCore/QuartzCore.h>

@interface TTXibViewController ()

@property (weak, nonatomic) IBOutlet TTSwitch *defaultSwitch;

@end

@implementation TTXibViewController
- (IBAction)sendEmail:(id)sender {

    UIGraphicsBeginImageContextWithOptions(self.view.frame.size, NO, 0.0);

    [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    NSData * data = UIImagePNGRepresentation(screenshot);
    [self emailImageWithImageData:data];
}

- (void)emailImageWithImageData:(NSData *)data
{
    MFMailComposeViewController *mailController = [[MFMailComposeViewController alloc] init];
    mailController.mailComposeDelegate = self;
    [mailController setSubject:@"Test Email"];
    [mailController setMessageBody:nil isHTML:NO];
    [mailController addAttachmentData:data mimeType:@"image/png" fileName:@"test.png"];
    [self.navigationController presentModalViewController:mailController animated:YES];
}

- (void)mailComposeController:(MFMailComposeViewController*)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error
{
    [self dismissModalViewControllerAnimated:YES];

}

@end

;

[spenrose]

I am not sure how to solve this problem without rewriting the switch to draw with core graphics. I am open to any ideas on how to change the way the masking currently works to fix it.

[hackiftekhar]

I wasted two days, but finally i had to create my own logic.

I have solved this problem by a tricky logic.

I created following code to get UIImage from UIView.subviews.
Actually i am having Subviews. And my subView's layer is masked by CAShapeLayer.
modify this code according to your requirement.

-(UIImage*) imageFromView:(UIView*)originalView
{
    //Creating a fakeView which is initialized as our original view.
    //Actually i render images on a fakeView and take screenshot of this fakeView.
    UIView *fakeView = [[UIView alloc] initWithFrame:originalView.frame];
            [fakeView setBackgroundColor:originalView.backgroundColor];
            [fakeView.layer setMasksToBounds:originalView.layer.masksToBounds];
            [fakeView.layer setCornerRadius:originalView.layer.cornerRadius];
            [fakeView.layer setBorderColor:originalView.layer.borderColor];
            [fakeView.layer setBorderWidth:originalView.layer.borderWidth];

            //Getting subviews of originalView.
            for (UIView *view in originalView.subviews)
            {
                //Getting screenshot of layer of view.
                UIGraphicsBeginImageContext(view.bounds.size);
                [view.layer renderInContext:UIGraphicsGetCurrentContext()];
                UIImage *imageLayer = UIGraphicsGetImageFromCurrentImageContext();
                UIGraphicsEndImageContext();

                //If it is masked view, then get masked image.
                if (view.layer.mask)
                {
                    //getting screenshot of masked layer.
                    UIGraphicsBeginImageContext(view.bounds.size);
                    [view.layer.mask renderInContext:UIGraphicsGetCurrentContext()];

                    //PNG Representation is most important. otherwise this masked image will not work.
                    UIImage *maskedLayerImage=[UIImage imageWithData:UIImagePNGRepresentation(UIGraphicsGetImageFromCurrentImageContext())];
                    UIGraphicsEndImageContext();

                    //getting image by masking original image.
                    imageLayer = [self maskImage:imageLayer withMask:maskedLayerImage];
                }

                //If imageLayer is pointing to a valid object, then setting this image to UIImageView, our UIImageView frame having exactly as view.frame.
                if (imageLayer)
                {
                    UIImageView *imageView = [[UIImageView alloc] initWithFrame:view.frame];
                    [imageView setImage:imageLayer];
                    [fakeView addSubview:imageView];
                }
            }

            //At the end, taking screenshot of fakeView. This will get your Original Image.
            UIGraphicsBeginImageContext(fakeView.bounds.size);
            [fakeView.layer renderInContext:UIGraphicsGetCurrentContext()];
            UIImage *previewCapturedImage = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();
            return previewCapturedImage;
        }
}

//Method is used to get masked image.
- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage
{
    CGImageRef maskRef = maskImage.CGImage; 
    CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
                                        CGImageGetHeight(maskRef),
                                        CGImageGetBitsPerComponent(maskRef),
                                        CGImageGetBitsPerPixel(maskRef),
                                        CGImageGetBytesPerRow(maskRef),
                                        CGImageGetDataProvider(maskRef), NULL, false);

    CGImageRef masked = CGImageCreateWithMask([image CGImage], mask);

    return [UIImage imageWithCGImage:masked];
}

[hk007]

Thanks hackiftekhar! Your tricky solution worked. Just had to modify a little according to my view setup.

[hackiftekhar]

most welcome.