I have a first NSArray firstArray and I do
firstArray
[firstArray removeAllObjects];
after I want fill it with the content of an other a
No, firstArray = secondArray will reassign the pointers, this is not the behavior you want. You want [firstArray addObjectsFromArray:secondArray]
firstArray = secondArray
[firstArray addObjectsFromArray:secondArray]
Since the firstArray is an NSArray, you will want to do this instead:
firstArray = [NSArray arrayWithArray:secondArray];