Returning Number of Items in Section iOS - ios

Question

Very straight forward question here; I'm using a UICollectionView and looking to display a certain number of images per section determined by a count of the images that match the section.
For example:
Category: x
# Images in Category: y
# Images In Section: y
I've got sorting everything into the categories down, and I can get the count for each category, but I'm not sure how to return the correct value for each image in the "Category" section. This is what I've got so far:
- (NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
// Category Delineater Here
for (int i = 0; i <= _categoryCount.count; i++)
{
PFQuery *tiredQuery = [[PFQuery alloc] initWithClassName:#"savedImages"];
[tiredQuery whereKey:#"imageCategory" equalTo:[_categoryCount objectAtIndex:0]];
[tiredQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)
{
if (!error)
{
NSLog(#"What does this return? %#", objects);
}
else
{
NSLog(#"This returns an error: %#", error);
}
}];
}
return _extractedImagesArray.count;
}
Currently, _extractedImagesArray.count is the total number of images that are downloaded. How to I change the amount returned in this section based on the number of images a particular category has?
EDIT: For Clarification of data structure:
Each image has a category affixed to it. The images are all placed in the same Class on Parse.
My ultimate goal is to get it to look similar to this ([x] representing an image in this case):
Category 1
X X X X X
Category 2
X X X
Category 3
X X X X
etc etc

Answer 1

This line looks like a problem:
[tiredQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)
The method you're using runs asynchronously, so you're not going to get the results back right away. -collectionView:numberOfItemsInSection: isn't going wait around for you to find the objects asynchronously and then count them -- you need to return the number of objects immediately.
It sounds like you'll probably need to do some processing ahead of time to determine the number of objects in each section, and then remember the counts somewhere so that you can provide them when asked by the collection view.

Answer 2

Looks like you are using Parse.
You should not make a call to the backend while reloading data. Try something like this:
- (void)getImages {
for (int i = 0; i <= _categoryCount.count; i++) {
PFQuery *tiredQuery = [[PFQuery alloc] initWithClassName:#"savedImages"];
[tiredQuery whereKey:#"imageCategory" equalTo:[_categoryCount objectAtIndex:0]];
[tiredQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
_extractedImagesArray = objects;
[collectionView reloadData];
}
else {
NSLog(#"This returns an error: %# %#", error, [error userInfo]);
}
}];
}
}
- (NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return _extractedImagesArray.count;
}
Here is an example of returning different amounts of items dependent no which section you are referencing. Remember, section 0 is always the first one.
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
switch (section) {
case 0:
return xNumber;
break;
case 1:
return yNumber;
break;
case 2:
return zNumber;
}
}