Uicollectionview Reloaddata Not Functioning Properly in iOS 7

reloadData not working for UICollectionView in iOS7

• After writing reloadItemsAtIndexPaths no need of writing again
  reloadData.
• Reload the respective collection View row using main thread.

Code Snippet:

[[NSOperationQueue  mainQueue]  addOperationWithBlock:^{

    // Reload the respective collection view row using the main thread.

    [self.collectionView reloadItemsAtIndexPaths:[self.collectionView indexPathsForVisibleItems]];

}];

UICollectionView Reload Data Not Working to update CollectionView

You can't update UI elements in a background thread. [self.collectionView reloadData] is called from parseRss which is itself called form parseFeed which is called by an operation on _queue. if _queue doesn't happen to be processed by the main thread, you will get unpredictable results in the collectionView and more likely crashes.

You should dispatch your call to [self.collectionView reloadData] to the main thread.

dispatch_async(dispatch_get_main_queue(), { self.collectionView.reloadData() })

(this is the Swift syntax, i'm not familiar with Obj-C, sorry)

UICollectionView does not reloadData

If you get the error on this line...

self.collectionView.reloadData()

.. then either self or collectionView could be nil. To check this just place a breakpoint on this line and check which is nil - either self or collectionView. If you do not know how to set breakpoints and check values in the debugger then please search for tutorials - it's easy, but to much to explain here. You will have to learn this anyway if you want to continue programming.

And: removing the "weak" from the collectionView is a bad idea because it could lead to a reference cycle and a memory leak.

UICollectionView won't reloadData() after UIImagePickerController dismisses

Your lookUpPhotos function is fine, but you can update the collectionView at the end of your query.

func lookUpPhotos() {

    let findPhotos = PFQuery(className: "Gallery")
    findPhotos.whereKey("dogID", equalTo: self.dogObjectID)
    findPhotos.orderByDescending("createdAt")
    findPhotos.findObjectsInBackgroundWithBlock { 
        (objects, error) -> Void in

        if let users = objects {
            for object in users { 
                self.photoData.addObject(object)
                print("Fetched \(self.dogSelectedName)'s \(self.photoData.count) Images") 
            } 
        }

        dispatch_async(dispatch_get_main_queue()) { () -> Void in
            self.collectionView.reloadData()
        }
    }
}

You can then call the lookUpPhotos function again once you send the data.

saveImage.saveInBackgroundWithBlock { (Bool, error) -> Void in
    if error != nil {
        print("There was an error")
    } else {
        print("New Gallery object saved: \(saveImage)")
        dispatch_async(dispatch_get_main_queue()) { () -> Void in
            self.dismissViewControllerAnimated(true) { () -> Void in
                self.lookUpPhotos()
            }
        }
    }
}

UICollectionView stuck in reloadData

Never do UIKit stuff from a background thread. So make sure reloadData is called on the main thread and don't modify the backing array from a background thread.

UICollectionView reloadData seems slow/laggy (not instantaneous)

Some possibilities:

• Your presumably recursive function to set the fonts is probably expensive.
• A few of the other Universal functions look like they might be expensive.
• It does not appear that you ever remove the button target and every time a cell is reused, you are adding additional targets to it.
• imageWithContentsOfFile: skips the cache; use imageNamed: instead.

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