Refreshing a UICollectionview

Question

Does anyone know how to reload/refresh a UICollectionView while the collection view is being displayed? Basically I'm looking for something similar to the standard reloadData method for a UITableview.

Maybe I am misunderstanding, but UICollectionView implements reloadData. — danh, Feb 07 '13 at 01:48

score 51 · Accepted Answer · edited Jun 27 '18 at 11:19

51

You can just call:

[self.myCollectionView reloadData];

Individual sections and items can also be reloaded:

[self.myCollectionView reloadSections:indexSet];
[self.myCollectionView reloadItemsAtIndexPaths:arrayOfIndexPaths];

edited Jun 27 '18 at 11:19

LinusGeffarth

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answered Feb 07 '13 at 01:58

Firo

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WFIW I believe the reason why people are coming across this is because they're used to calling [myTableView reloadData] but with UICollectionViews you must call [myCollectionView.collectionView reloadData]. – capikaw Jun 12 '13 at 17:08
[self.myCollectionView reloadData]; call only once. want to reload all data. – Anand Prakash Apr 12 '17 at 10:50

score 11 · Answer 2 · answered Dec 21 '13 at 21:48

11

[self.collectionView reloadData];

answered Dec 21 '13 at 21:48

Lücks

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While this will indeed achieve the desired results, using reloadData redraws all the cells and can affect performance. – DrunkenBeard Jul 23 '14 at 13:19
Not a good idea, because reloading the full table you get bad perfomance and energy is drawn. – Karsten Nov 11 '16 at 11:33

score 1 · Answer 3 · answered Nov 11 '16 at 11:47

The correct and best way is to use

NSMutableArray *indexPaths = [NSMutableArray array];
//prepare some data
//batchupdate as block
[self.collectionView performBatchUpdates:^{
    //operations like delete
   [self.collectionView deleteSections:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(1, count)]];
    [self.collectionView insertItemsAtIndexPaths:indexPaths];
} completion:^(BOOL finished) {
    // call something when ready
    }
}];

and all gets precomputed an nicely animated. The best practice is to first remove and than add all elements, to avoid conflicts.

Refreshing a UICollectionview

3 Answers3

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