Record
NSString * imageTitle = [NSString stringWithFormat:@"landing_load%i", x];
means that you have a pair of graphics files for any resource - both "filename.png" and "filename@2x.png". Or, alternatively, it can be used as "alias" for only "filename.png" If you have only "filename@2x.png", you have two possible variants: 1. Use something like that
NSString * imageTitle = [NSString stringWithFormat:"landing_load%i@2x", x];
or have both of files ("filename.png" and "filename@2x.png") for any resource.