Xcode - Multiple photo filters - ios

Question

I'm creating a photo app that involves filters. The filters work, but they stay permanent and overlap each other. I want, for example, the sepia filter to be removed from the image and replaced with the instant filter when the instant filter button is pressed. How do I achieve this? Here is some code from the project:
- (IBAction)sepiaFilter:(id)sender {
CIImage *beginImage = [CIImage imageWithData: UIImagePNGRepresentation(self.picture.image)];
CIContext *context = [CIContext contextWithOptions:nil];
CIFilter *filter = [CIFilter filterWithName:#"CISepiaTone" keysAndValues:kCIInputImageKey, beginImage, #"inputIntensity", [NSNumber numberWithFloat:0.8], nil ];
CIImage *outputImage = [filter outputImage];
CGImageRef cging = [context createCGImage:outputImage fromRect:[outputImage extent]];
self.picture.image = [UIImage imageWithCGImage:cging];
CGImageRelease(cging);
}
- (IBAction)instantFilter:(id)sender {
CIImage *beginImage = [CIImage imageWithData: UIImagePNGRepresentation(self.picture.image)];
CIContext *context = [CIContext contextWithOptions:nil];
CIFilter *filterTwo = [CIFilter filterWithName:#"CIPhotoEffectInstant" keysAndValues:kCIInputImageKey, beginImage, nil ];
CIImage *outputImage = [filterTwo outputImage];
CGImageRef cging = [context createCGImage:outputImage fromRect:[outputImage extent]];
self.picture.image = [UIImage imageWithCGImage:cging];
CGImageRelease(cging);
}
(I actually have nine filters, but I just need an idea on how to do this) Thanks for any help

Answer 1

Its quite simple. You are using self.picture.image for input as well as output. Keep an original UIImage separately for input, and use self.picture.image only for output, so the only thing in your code changes is the first line of both the filters ie
CIImage *beginImage = [CIImage imageWithData: UIImagePNGRepresentation(self.originalImage)];
Hope this helps.