Refresh control with UICollectionView reloadData issue - ios

Question

I continue refining the implementation of my UICollectionViewController with Parse and this time I'm dealing with an issue that it might be related to cache or maybe the reloadData method itself.
Maybe you can help me identify the source of this strange behavior that I better show you on a short video to save time:
Refreshing issue video
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
refreshControl = [[UIRefreshControl alloc] init];
[refreshControl addTarget:self action:#selector(refershControlAction) forControlEvents:UIControlEventValueChanged];
[self.collectionView addSubview:refreshControl];
[self queryForTable];
}
Then on my refreshControlAction:
- (void)refershControlAction
{
NSLog(#"Reload grid");
// The user just pulled down the collection view. Start loading data.
[self queryForTable];
[refreshControl endRefreshing];
}
The query method is like this:
- (void)queryForTable
{
PFQuery *query = [PFQuery queryWithClassName:#"Photo"];
query.limit = 15;
[query orderByAscending:#"createdAt"];
[query setCachePolicy:kPFCachePolicyNetworkOnly];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
// The find succeeded.
NSLog(#"Successfully retrieved %d photos.", objects.count);
[self.collectionView reloadData];
gridImages = [[NSMutableArray alloc] initWithCapacity:objects.count];
// Do something with the found objects
for (PFObject *object in objects) {
PFFile *thumbnail = [object objectForKey:#"thumbnail"];
[thumbnail getDataInBackgroundWithBlock:^(NSData *data, NSError *error) {
if (!error) {
// Now that the data is fetched, update the cell's image property with thumbnail
//NSLog(#"Fetching image..");
[gridImages addObject:[UIImage imageWithData:data]];
//NSLog(#"Size of the gridImages array: %d", [gridImages count]);
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
}
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
}
This doesn't happen on my PFQueryTableViewController where I'm performing the exact same query and where I'm also using the iOS 6 refresh control instead of the one provided by Parse.
Do you see something that could be causing this behavior?

Answer 1

I could see some prob in your code.
- (void)refershControlAction
{
NSLog(#"Reload grid");
// The user just pulled down the collection view. Start loading data.
[self queryForTable];
[refreshControl endRefreshing];
}
you endRefreshing before your query get completed, so it is wrong use. You should put [refreshControl endRefreshing] in your-(voi)queryForTable` when the query complete
The other problem is I don't know if you get your datasource updated when the query completed.