Cloning/Copying an NSMutableArray in Objective C

Question

How are arrays cloned or copied into other arrays in Objective-C?

I would like to have a function which when passed in an NSMutableArray, it takes the array and fills up another array with the content.

Is it as simple as someArray = passedInArray? OR os there some initWith function?

Nikita Rybak · Accepted Answer · 2011-02-20 15:53:43Z

14

This should work good enough

[NSMutableArray arrayWithArray:myArray];

Also, copy method probably does the same

[myArray copy];

But simple assignment won't clone anything. Because you assign only a reference (your parameter probably looks like NSMutableArray *myArray, which means myArray is a reference).

answered Feb 20, 2011 at 15:53

Nikita Rybak

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1 Comment

TomSwift Over a year ago

Invoking copy on a mutable array will return a new non-mutable array. Invoke mutableCopy instead if you want another mutable array.

Community · Accepted Answer · 2017-05-23 12:07:01Z

5

Don't mind but your question seems to be a duplicate deep-copy-nsmutablearray-in-objective-c; however let me try.

Yeah its not so simple, you have to be somewhat more careful

/// will return a reference to myArray, but not a copy
/// removing any object from myArray will also effect the array returned by this function
-(NSMutableArray) cloneArray: (NSMutableArray *) myArray {
    return [NSMutableArray arrayWithArray: myArray];
}

/// will clone the myArray
-(NSMutableArray) cloneArray: (NSMutableArray *) myArray {
    return [[NSMutableArray alloc] initWithArray: myArray];
}

Here is documentation article Copying Collections

edited May 23, 2017 at 12:07

CommunityBot

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answered Feb 20, 2011 at 16:11

Waqas Raja

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1 Comment

JaredH Over a year ago

do you mean to use initWithArray:copyItems:YES for that second method? As it stands, I believe those two methods are identical.

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