Should I fix Xcode 5 'Semantic issue: undeclared selector'?

Question

I'm trying to upgrade my app with Xcode5 but encountered a number of 'Semantic issues' in a third party library (being MagicalRecord). The quickest way to 'fix' this might be using the:

#pragma GCC diagnostic ignored "-Wundeclared-selector" 

(from: How to get rid of the 'undeclared selector' warning)

compiler directive, but my gut-feeling says this is not the appropriate way to do this. A small code sample with the above error:

+ (NSEntityDescription *) MR_entityDescriptionInContext:(NSManagedObjectContext *)context {      if ([self respondsToSelector:@selector(entityInManagedObjectContext:)])      {         NSEntityDescription *entity = [self performSelector:@selector(entityInManagedObjectContext:) withObject:context];         return entity;     }     else     {         NSString *entityName = [self MR_entityName];         return [NSEntityDescription entityForName:entityName inManagedObjectContext:context];     } } 

where the entityInManagedObjectContext: method is not defined anywhere.

Any suggestions on how to best fix these types of errors, thanks in advance?!

Answer 1

Yes you should.

instead of doing this:

[self.searchResults sortUsingSelector:@selector(compareByDeliveryTime:)]; 

you should do this:

SEL compareByDeliveryTimeSelector = sel_registerName("compareByDeliveryTime:"); [self.searchResults sortUsingSelector:compareByDeliveryTimeSelector]; 

Answer 2

You just need to declare a class or protocol that contains the selector. For example:

//  DeliveryTimeComparison.h #import <Foundation/Foundation.h>  @protocol DeliveryTimeComparison <NSObject>  - (void)compareByDeliveryTime:(id)otherTime;  @end 

And then simply #import "DeliveryTimeComparison.h" in any class where you plan to use @selector(compareByDeliveryTime:).

Or alternatively, just import the class header for any object that contains a "compareByDeliveryTime:" method.