CODEWITHSUNDEEP
objective-cnsmutablearraynsmutabledictionary
Samantha Catania
Samantha Catania

Reputation: 5316

Manipulate Arrays in NSDictionary

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?

Upvotes: 1

Views: 319

Answers (2)

Samantha Catania
Samantha Catania

Reputation: 5316

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"];

Upvotes: 1

picciano
picciano

Reputation: 22701

Are you loading the NSDictionary from a file or URL by any chance? From the API docs: "The objects contained by this dictionary are immutable, even if the dictionary is mutable."

Upvotes: 1

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