Is there an NSMutableDictionary literal syntax for deleting an element?

Question

There is literal syntax for adding an object and modifying an object in NSMutableDictionary, is there literal syntax for deleting an object?

Answer 1

Yes, but ... :-)

This is not supported by default, but the new syntax for setting dictionary items uses the setObject:forKeyedSubscript: method, and not setObject:forKey: Thus, you can write a category that replaces the former, and either installs or removes the item:

 @implementation NSMutableDictionary (RemoveWithNil) - (void) setObject:(id)obj forKeyedSubscript:(id<NSCopying>)key { if (obj) [self setObject:obj forKey:key]; else [self removeObjectForKey:key]; } @end 

Add this to your application and then:

 dict[aKey] = nil; 

will delete the item.

Answer 2

No. No. I tried to find a link to the proof, but failed :)

Answer 3

Starting with iOS 9 and macOS 10.11, these are two equivalents:

  [dictionary removeObjectForKey:@"key"]; dictionary[@"key"] = nil; 

See Foundation Release Notes (find the NSMutableDictionary subscript syntax change header).