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Editorial Team
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Asked: 2026-06-11T10:19:54+00:00

Does the objectForKey: method of NSMutableDictionary class return a copy of the object? If

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Does the objectForKey: method of NSMutableDictionary class return a copy of the object?

If I have a NSMutableArray stored inside a NSMutableDictionary and I make some modifications (like adding an object) to the array that I accessed with the objectForKey: method of the dictionary will those modifications be valid for the array stored inside the dictionary?

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1 Answer

  1. Editorial Team

    No, it does not return a copy.

    NSMutableArray *array = [NSMutableArray new];
NSMutableDictionary *dict = [NSMutableDictionary new];

NSLog(@"local instance of array: %p", array);

[dict setObject: array forKey: @"key"];

NSLog(@"returned from dictionary: %p", [dict objectForKey: @"key"]);

    Output:

    2012-09-16 14:06:36.879 Untitled 3[65591:707] local instance of array: 0x7f98f940a2f0
2012-09-16 14:06:36.884 Untitled 3[65591:707] returned from dictionary: 0x7f98f940a2f0

    You are returned the same pointer, meaning the object has not been copied.

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