Question

I tried to manipulate an array in an NSMutableDictionary directly:

[[myDictionary objectForKey: @"key"] addObject: object];

This doesn’t work! I even tried type casting:

[(NSMutableArray*)[myDictionary objectForKey: @"key"] addObject: object];

This didn’t work either!

The only way that worked was:

NSMutableArray *array = [myDictionary objectForKey: @"key"];
[array addObject: object];
[myDictionary setObject: array forKey: @"key"]

Is there a way to manipulate the array in the dictionary similar to the first code snippet; i.e. without having to create a new array, manipulating it and then saving it?

Answer 1

The problem was that I wasn’t allocation the array within the NSMutable Dictionary i.e. before adding objects use the following code:

[myDictionary addObject: [[NSMutableArray alloc]init] forKey: @"key"];