(iOS) Image masking Objective-C / Swift

c-mask.mm

//http://www.innofied.com/implementing-image-masking-in-ios/

- (UIImage*) maskImage:(UIImage *) image withMask:(UIImage *) mask
{
    CGImageRef imageReference = image.CGImage;
    CGImageRef maskReference = mask.CGImage;
    
    CGImageRef imageMask = CGImageMaskCreate(CGImageGetWidth(maskReference),
                                             CGImageGetHeight(maskReference),
                                             CGImageGetBitsPerComponent(maskReference),
                                             CGImageGetBitsPerPixel(maskReference),
                                             CGImageGetBytesPerRow(maskReference),
                                             CGImageGetDataProvider(maskReference),
                                             NULL, // Decode is null
                                             YES // Should interpolate
                                             );
    
    CGImageRef maskedReference = CGImageCreateWithMask(imageReference, imageMask);
    CGImageRelease(imageMask);
    
    UIImage *maskedImage = [UIImage imageWithCGImage:maskedReference];
    CGImageRelease(maskedReference);
    
    return maskedImage;
}


//USE
UIImage *image=[UIImage imageNamed:@"image2.png"];
UIImage *mask=[UIImage imageNamed:@"mask6.png"];
UIImage *newimage=[self maskImage:image withMask:mask];
self.imageView.image=newimage;

swift-mask.swift

Swift

func maskImage(image:UIImage, mask:(UIImage))->UIImage{
        
     let imageReference = image.CGImage
     let maskReference = mask.CGImage
        
     let imageMask = CGImageMaskCreate(CGImageGetWidth(maskReference),
     CGImageGetHeight(maskReference),
     CGImageGetBitsPerComponent(maskReference),
     CGImageGetBitsPerPixel(maskReference),
     CGImageGetBytesPerRow(maskReference),
     CGImageGetDataProvider(maskReference), nil, true)
        
     let maskedReference = CGImageCreateWithMask(imageReference, imageMask)
        
     let maskedImage = UIImage(CGImage:maskedReference!)
        
     return maskedImage
}


//USE
let image = UIImage(named: "image2.png")
let maskingImage = UIImage(named: "mask6.png")
imageView.image = maskImage(image!, mask: maskingImage!)

SWIFT 3

func maskImage(image: UIImage, withMask maskImage: UIImage) -> UIImage {

    let maskRef = maskImage.cgImage

    let mask = CGImage(
        maskWidth: maskRef!.width,
        height: maskRef!.height,
        bitsPerComponent: maskRef!.bitsPerComponent,
        bitsPerPixel: maskRef!.bitsPerPixel,
        bytesPerRow: maskRef!.bytesPerRow,
        provider: maskRef!.dataProvider!,
        decode: nil,
        shouldInterpolate: false)

    let masked = image.cgImage!.masking(mask!)
    let maskedImage = UIImage(cgImage: masked!)

    // No need to release. Core Foundation objects are automatically memory managed.

    return maskedImage

}

not working 😟 in Swift

func drawMaskImage(_ mask:UIImage) -> UIImage? {
        guard let imageReference = self.cgImage else { return nil };
        let maskReference = mask.cgImage;
        if let maskReference = maskReference {
            let imageMask = CGImage(maskWidth: maskReference.width,
                                    height: maskReference.height,
                                    bitsPerComponent: maskReference.bitsPerComponent,
                                    bitsPerPixel: maskReference.bitsPerPixel,
                                    bytesPerRow: maskReference.bytesPerRow,
                                    provider: maskReference.dataProvider!,
                                    decode: nil, shouldInterpolate: true)
               
            let maskedReference = imageReference.masking(imageMask!)
            let maskedImage = UIImage(cgImage:maskedReference!)
            return maskedImage
        }
        return nil;
    }