Merge two arrays while preserving the original array order

Question

I\'ve writing an application that requests data from an external source (Twitter), which is returned as an ordered array in chronological order:

External array

Answer 1

You should use the array as a stack, so the old items get pushed below the newer ones. You could achieve that by adding every element at the last position using [myArray addObject:newObject];. You will have to iterate backwards in the original array in order to insert them from oldest to newest. You can achieve that by doing :

for(NSUInteger index = [newArray count] - 1; i == 0; i--)
{
    NSDictionary*object = [newArray objectAtIndex:index];
    [myArray addObject:object];
}

This way you will get the array you need

Cheers

Answer 2

Just use the new array as the first array and add the old items after.

NSMutableArray *newArray = [NSMutableArray arrayWithCapacity:externalArray.count + myArray.count];
for(NSDictionary *item in externalArray) {

    // Need loop so I can do some extra stuff here with each item object (not shown in this example.)
    [newArray addObject: item];
}

[newArray addObjectsFromArray:myArray];

Answer 3

NSArray *newArray = [externalArray arrayByAddingObjectsFromArray:myArray];
[myArray release];
myArray = [newArray mutableCopy];

Any reason not to do this?