CODEWITHSUNDEEP
objective-cios
Saturn
Saturn

Reputation: 18149

Do I have to release deep-copied NSMutableDictionary produced this way?

I am doing deep copies of NSMutableDictionary with this: https://stackoverflow.com/a/5453600/555690

Like this:

NSMutableDictionary *myCopy = [originalMutableDictionary mutableDeepCopy];

Do I have to release myCopy?

Upvotes: 1

Views: 131

Answers (2)

Dan Rosenstark
Dan Rosenstark

Reputation: 69757

I'm assuming you're not using ARC. The answer should be "yes" since it's created with copy. See the NARC rules here:

Do you need to release parameters of methods at the end of them in Objective-C?

In that particular code, the ret is created using dictionaryWithObjects so it would already be autoreleased, but then there's an extra retain that's called explicitly. So the answer is... still "yes," which follows the ownership policy.

Upvotes: 4

jscs
jscs

Reputation: 64002

The code adds a retain to the return value right when it's created and doesn't balance that before returning:

NSMutableArray *ret = [[NSMutableArray arrayWithObjects:cArray count:count] retain];

// The newly-created array retained these, so now we need to balance the above copies
for (unsigned int i = 0; i < count; ++i)
    [cArray[i] release];

return ret;

This is in accordance with Cocoa naming convention and memory management rules, which say that a method with mutableCopy in its name returns an owned value.

The dictionary you get from this method is indeed owned by you and must be released by you.

Note that the middle lines in the snippet above are ensuring that the objects contained in the dictionary are only owned by the dictionary itself; you are not directly responsible for those. They'll be released when the dictionary is destroyed.

Upvotes: 2

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