How to do right iOS architecture?

Recently, I have done a test task for the iOS developer role. My app took a photos from user library and applied a different filters for them. There was some conditions, but it doesn't matter now.

In method - (void)applyFilterWithName:(NSString *)filterName I had a code, which applied a filters to photo.

        // Get full image
        NSURL *url = [contentEditingInput fullSizeImageURL];
        int orientation = [contentEditingInput fullSizeImageOrientation];
        CIImage *inputImage = [CIImage imageWithContentsOfURL:url options:nil];
        inputImage = [inputImage imageByApplyingOrientation:orientation];

        // Add filter
        CIFilter *filter = [CIFilter filterWithName:filterName];
        [filter setDefaults];
        [filter setValue:inputImage forKey:kCIInputImageKey];
        CIImage *outputImage = [filter outputImage];

As a result I was said that my code has permanent reinitialization CIFilter and as a result the architecture and structure of the project suffer.

Can me somebody explain how to make that architecture did not suffer and there was constant re-initialize CIFilter.

And why that is the problem? I created instance CIFilter *filter - and this is a problem as permanent reinitialisation. At the same time I created instance NSURL *url and CIImage *imageoutput - and this is not a permanent reinitalisation.

Can anybody help me to understand this. Thanks a lot.