If they are photos, you can have NSData for those photos as a final result. Then you can save the data of the photo in a directory inside your application.
Best place to store that kind of data/files in Application Support Directory.
NSString *appSupportDir = [NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES) lastObject];
NSString *photoPath = [appSupportDir stringByAppendingPathComponent:@"photo1.png"];
UIImage *image; //image you got from the camera inside your app
NSData *photoData = UIImagePNGRepresentation(image);
[photoData writeToFile:photoPath atomically:YES];