dynamically created pointer or 'instance name'

[natronp]

In obj. c can you create a pointer by combining a string with a variable value?

something like so:

NSMutableArray["myArray"+i] = [[NSMutableArray alloc]init];

where 'i' is a loop variable/int?

[bytor99999]

Be a bit more specific please.

This might be something similar to what you are looking for

NSError *error = nil;
    if (managedObjectContext != nil) {
        if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {

Where that error variable is used with &error. It might help.

Mark

[natronp]

i want to create an array called "myArray5"

where "5" is added to the string "myArray" and represents the value of an int variable.

[RLScott]

Originally Posted by natronp

i want to create an array called "myArray5"

where "5" is added to the string "myArray" and represents the value of an int variable.

No, Objective-C variable names must be explicitly known at compile time. You cannot generate variable names at run time. Anyway, why do you care what the variable name is? The variable name is just a convenience for the programmer. It has no effect on the user's experience of your app.

[natronp]

Anyway, why do you care what the variable name is?

I want to separate one large array of objs into separate arrays of 16 objs each.

so in my loop i do something like this:

if( i%16 == 0)
		{
		//we have a multiple of 16?
			[self galleryArray] addObject: currArray];  push array filled by previous iterations of loop into another array
			[currArray release]; //let go of it, the other array is now owner
			NSMutableArray *currArray = [[NSMutableArray alloc]init]; //create a new array to start filling in next iteration of loop
			
			
			
		}

so that on every sixteenth item in the array, i push the current array into a third array which i will use later. I was hoping that by releasing the 'currArray' first, it would only be retained by the 'galleryArray' and i could alloc/init another 'currArray' and start filling it. This is not the case however as the way i'm doing it seems to push everything into the first 'instance' of 'currArray'.

Ultimately i don't care what the array is called, i'm just using the array temporarily before i push it as an object in another array. I only care in that it seems that using the same pointer results in everything being pushed into the same array...

it would be very convenient to be able to temporarily refer to these temporary arrays by the loop iteration variable, do stuff with them and then get rid of them...

of course i'm assuming there is a better way of doing this in obj c that in my noobness, i'm unaware of!

[Shod]

Originally Posted by natronp

I want to separate one large array of objs into separate arrays of 16 objs each.

so in my loop i do something like this:

if( i%16 == 0)
		{
		//we have a multiple of 16?
			[self galleryArray] addObject: currArray];  push array filled by previous iterations of loop into another array
			[currArray release]; //let go of it, the other array is now owner
			NSMutableArray *currArray = [[NSMutableArray alloc]init]; //create a new array to start filling in next iteration of loop
			
			
			
		}

so that on every sixteenth item in the array, i push the current array into a third array which i will use later. I was hoping that by releasing the 'currArray' first, it would only be retained by the 'galleryArray' and i could alloc/init another 'currArray' and start filling it. This is not the case however as the way i'm doing it seems to push everything into the first 'instance' of 'currArray'.

You do not achieve that because you are defining a new variable called currArray inside the if block and as soon as that block ends (the line after) that variable is out of scope. So try and replace:

NSMutableArray *currArray = [[NSMutableArray alloc]init];

with:

currArray = [[NSMutableArray alloc]init];

or you could just do:

[currArray removeAllObjects];

without releasing currArray before ofc.

[nobre84]

out of date reply, better answered above ^

[natronp]

man, i had no idea that an if statement had its own scope. thanks for the info.

so now i have:

for(int i=0; i < self.pics.count; ++i)
	{
		
		
		tempObj = [[ItemPic alloc]init];
		tempObj = [[self pics] objectAtIndex:i];
		
		
		[currArray addObject:tempObj]; //add to current array
		
		[tempObj release];
		tempObj=nil;
		
		if( i%16 == 0 )
		{
			NSLog(@"we have multiple of 16");
			//we have a multiple of 16?
			[[self galleryArray] addObject: currArray];
			[currArray release];
			//currArray = nil;
			currArray = [[NSMutableArray alloc]init];
			
		}
		
		
		if(i==self.pics.count-1)
		{
			NSLog(@"end of loop!");
			NSLog(@"GalleryArray count: %i", self.galleryArray.count);
			//we're done paging results into array(s)
			[self loadPage:1];
		}
		
					}

but my:

if( i%16 == 0 )
		{

must be triggering on the first iteration ( 0/16=0 ) which is not what i want. It's splitting the 23 or so objects in my master array into two arrays, one with one object and one with 16. I realize this is a whole "nother" issue, but what can i do to clean this up?

[Shod]

well there are many solutions:

you could change the if statement like this:

if ((i % 16 == 0) && i) { ... }

since in the first iteration i is equal to 0, the if will evaluate to false.

Or you could check the size of currArray instead

if (currArray.count == 16) { ... }

and I'm sure there are many other ways.

By the way I just noticed these 2 lines on your code:

tempObj = [[ItemPic alloc]init];
tempObj = [[self pics] objectAtIndex:i];

What are you doing here is bad, you are leaking memory, because you are allocating an ItemPic object in the first line, and in the second line you are assigning tempObj to another object, losing the reference to the ItemPic object created on the line before, thus you will never be able to release it. So just remove the first line, since it is completely useless. And after that remove also those lines:

[tempObj release];
tempObj=nil;

Since you have not allocated tempObj, you do not have to release it.

[natronp]

nevermind. i think i found the problem with breakpoints and it's outside my loop. Thanks for the suggestion to use the array count vs. modulus!