Merging two images in objective-c

While researching about image manipulation for my next project, I came across an interesting piece of code, using which, we can merge two images into a single image. Here's the code:

-(UIImage*)mergeImage:(UIImage*)mask overImage:(UIImage*)source inSize:(CGSize)size
{
//Capture image context ref
UIGraphicsBeginImageContext(size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

//Draw images onto the context
[source drawInRect:CGRectMake(0, 0, source.size.width, source.size.height)]; 
[mask drawInRect:CGRectMake(0, 0, mask.size.width, mask.size.height)]; 

return viewImage;

}


Got the reference from here.