Question

I have an Model Class. When I call a the method “setter”, I set some String values to the attributes of my object. After the attributes are set, the method returns the new Object which is stored in the NSMutableArray *eintraegeSortiert.

Now, I need a new Object. I think I have to remove the pointer and set it again. If I don’t remove the pointer, all the objects stored in the mutable array will change too and I have stored the same object a 100 times in that mutable array. I have tried in multiple ways, without getting it right. What am I doing wrong? My code:

NSMutableArray *eintraegeSortiert = [NSMutableArray array];
for (int i = 0; i < ([mArray count] / 11) ; i++) {
        Vertretung *vertretung = [[Vertretung alloc] init];
        [eintraegeSortiert addObject:[self setter:mArray :vertretung]];
    }

Answer 1

I think you’re not really understanding how the code you’ve written works. Let’s take a look at it:

NSMutableArray *eintraegeSortiert = [NSMutableArray array];
for (int i = 0; i < ([mArray count] / 11) ; i++) {
    Vertretung *vertretung = [[Vertretung alloc] init];
    [eintraegeSortiert addObject:[self setter:mArray :vertretung]];
}

So step by step:

NSMutableArray *eintraegeSortiert = [NSMutableArray array];

Creates a new mutable array and assigns it to eintraegeSortiert

for (int i = 0; i < ([mArray count] / 11) ; i++) {

We’re going to loop [mArray count] / 11 times.

Vertretung *vertretung = [[Vertretung alloc] init];
[eintraegeSortiert addObject:[self setter:mArray :vertretung]];

Now, this is creating a variable within the current scope called vertretung. You call alloc/init. That will return a pointer to a new Vertretung object. For example this might be at memory location 0x12345678. Then you add that to the array.

Then we get to the end of the current scope and loop back around the for-loop. That means the variable vertretung goes out of scope.

Then when you loop around again, that same code runs again and again. But now the alloc/init will create an entirely new Vertretung object (maybe pointing to memory location 0xabcdef00 and add that to the array.

So no, it’s not the same object being added to the array multiple times.

Not sure what’s going on in setter:: – maybe post that as well if you’re still having issues.