NSMutableArray - Add array at start

Question

It is a simple pull to refresh case. I have data loaded into table and have a mutable data array at back-end, I receive a array of new data and want to add this complete array at start of existing array.

One workaround is to create new array with new arrived data and then add previous array into it using addObjectsFromArray: method. Is there some workaround to add new data array to the start of previous array directly?

nhgrif · Accepted Answer · 2014-03-19T00:24:15.563

59

First, build an NSIndexSet.

NSIndexSet *indexes = [NSIndexSet indexSetWithIndexesInRange:
    NSMakeRange(0,[newArray count])];

Now, make use of NSMutableArray's insertObjects:atIndexes:.

[oldArray insertObjects:newArray atIndexes:indexes];

Alternatively, there's this approach:

oldArray = [[newArray arrayByAddingObjectsFromArray:oldArray] mutableCopy];

edited Mar 19 '14 at 00:24

answered Mar 18 '14 at 22:55

nhgrif

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The alternative solution is the simplest solution for me. (y) – Prasanna Jun 10 '17 at 07:41

score 2 · Answer 2 · answered Mar 18 '14 at 22:54

2

NSMutableArray offers the insertObjects:atIndexes: method, but it's easier to append the way you suggest using addObjectsFromArray:.

answered Mar 18 '14 at 22:54

Wain

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score 1 · Answer 3 · answered Mar 18 '14 at 22:55

1

-insertObject:atIndexes: is easy enough, and should (I believe) be more efficient than using -addObjects and swapping arrays. It'd probably end up looking something like this:

[existingResults addObjects:newResults atIndexes:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, newResults.count)]]`

answered Mar 18 '14 at 22:55

Siobhán

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Simple and nice:) I believe newResults.count should be newResults.count-1. – Adnan Mar 18 '14 at 23:01
I don't think so; the second argument to NSMakeRange() is the count, not the ending index. But thanks! :-) – Siobhán Mar 19 '14 at 00:14

score 1 · Answer 4 · answered Mar 18 '14 at 22:58

1

Creating a new array is probably your best solution, but you can also use a loop

NSUInteger index;

index = 0;
for ( id item in sourceArray )
{
    [destArray insertObject:item atIndex:index];
    index++;
}

answered Mar 18 '14 at 22:58

user3386109

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score 0 · Answer 5 · edited Jun 08 '15 at 10:48

0

Just simple way:

NSMutableArray *arrayTmp = [firstArr addObjectsFromArray:myArray];
myArray = arrayTmp;

edited Jun 08 '15 at 10:48

Kevin Brown-Silva

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answered Jun 08 '15 at 08:24

Nghia Luong

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NSMutableArray - Add array at start

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