Copying the contents of an NSMutableDictionary into another NSMutableDictionary?

Question

I have an NSMutableDictionary each element of which is another dictionary. What is the best way I can copy its contents into another NSMutableDictionary? I've tried using:

firstDictionary = [NSMutableDictionary dictionaryWithDictionary:secondDictionary];

However not sure if this is the best way to do it.

As minimum, it's the most descriptive. Why do you think it's not the best? Do you need a deep or shallow copy of elements? — Schultz9999, Jan 05 '11 at 02:44
Deep copy means you have to make a copy of every single field of each element (which in turn means deep copy of fields' fields and so on). That functionality is not provided by any collection class. You have to take care of that yourself. — Schultz9999, Jan 05 '11 at 03:07
Already posted [click here][1].. ?Hope you help... [1]: http://stackoverflow.com/a/12315674/1317127 — Ashvin, Sep 07 '12 at 09:47

score 17 · Answer 1 · answered Apr 26 '11 at 02:43

You can also jump between mutable and non-mutable dictionaries using copy and mutableCopy.

- (void) someFunc:(NSMutableDictionary *)myDict {
    NSDictionary *anotherDict = [myDict copy];
    NSMutableDictionary *yetAnotherDict = [anotherDict mutableCopy];
}

score 6 · Accepted Answer · edited Jan 11 '17 at 09:26

6

Check the NSDictionary initWithDictionary:copyItems: method.

It it enables deep copying of elements thru calling copyWithZone: method of item's class. You will have to take care of copying the fields yourself within the method.

edited Jan 11 '17 at 09:26

Spartacus9

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answered Jan 05 '11 at 03:15

Schultz9999

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score 0 · Answer 3 · answered Sep 05 '13 at 13:22

0

Conform to NSCopying Protocol and do copyWithZone on every object.

If NsMutableDictionary contains another dictionary, which contains another dictionary,, then you need to do copyWithZone on each dictionary at all levels.

answered Sep 05 '13 at 13:22

Thasif Sheik

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score 0 · Answer 4 · answered Jan 05 '11 at 02:53

What do you mean by "best"?
Anyway, I listed some ways here:

firstDictionary = [NSMutableDictionary dictionaryWithDictionary:secondDictionary];
[[NSDictionary alloc] initWithDictionary:secondDictionary]; //don't forget to release later
using deep copy
using shallow copy

Copying the contents of an NSMutableDictionary into another NSMutableDictionary?

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