cellForItemAtIndexPath is not called for collectionView

Question

I have taken UICollectionView in storyboard. I have set datasource and delegate also. below method is called

 - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
 return 4;
}

But - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath is not called.

Attaching screenshot of properties of UICollectionView. Any idea about this problem?

Now collectionView is visible if I hide the navigationBar. In have set top constraint Myheader Collection View.top = Top Layout Guide.bottom + 64 thought it is at top of controller. and I am receiving follwing warning after completion of method -- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath.

Warning: nable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. ( "<_UILayoutSupportConstraint:0x7fda80dcff20 V:[_UILayoutGuide:0x7fda830006f0(0)]>", "<_UILayoutSupportConstraint:0x7fda80daca10 V:|-(0)-[_UILayoutGuide:0x7fda830006f0] (Names: '|':UIView:0x7fda80efb580 )>", "", "" )

Will attempt to recover by breaking constraint

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in may also be helpful.

Is the `numberOfItemsInSection` called? How many `sections` did you specify? — luk2302, May 11 '16 at 11:50
what do you see after running the app ? one item or not even one ? — Shubhank, May 11 '16 at 11:52
Try to increase the height of your collectionView. If it doesn't fit, it may not try to show an item (even if in theory the contentSize and the "visible" frame are different and shouldn't be an issue). — Larme, May 11 '16 at 11:56
Try to set delegate and datasource programmatically on viewDidLoad — Kevin Mac, May 11 '16 at 11:56
if you dont even see one, i would suggest giving a background color to collectionview and running and see if that comes up with a color. if it doesnt , i think its a autolayout issue — Shubhank, May 11 '16 at 11:57
@Shubhank done that.collectionView is displaying but cell of collectionView is not displaying. `- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath` is not calling.... — Payal Maniyar, May 11 '16 at 11:58
Your designed cell should be only one. Height/Width should be fixed at runtime and you have to return cell based on identifier. — Ashish Kakkad, May 11 '16 at 12:00
@AshishKakkad `- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath` method is not calling... — Payal Maniyar, May 11 '16 at 12:01
Put your code so it is easy to find what is the issue, From which method you are trying to call collectionview reload method? — Kevin Mac, May 11 '16 at 12:03
@KevinMac `-(void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; [myheaderCollectionView reloadData]; }` — Payal Maniyar, May 11 '16 at 12:09
@PayalManiyar Please share your project with scenario you are facing(Demo project). It may help to figure your problem out. — Amit Bhavsar, May 11 '16 at 12:19
`- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{ CGSize size= CGSizeMake(collectionView.frame.size.width/4, 34); NSLog(@"collection view : %@",collectionView); return size; }` — Payal Maniyar, May 11 '16 at 12:21
try to add datasourse and delegate to self manually also in view did load — KDeogharkar, May 11 '16 at 12:22
Try adding width constraint because cellForItemAtIndexPath will not called if the height and width constraints is not properly set. — Surya Subenthiran, May 11 '16 at 12:36
**collection view : ; layer = ; contentOffset: {0, -64}; contentSize: {320, 0}> collection view layout: ** `contentOffset: {0, -64}; contentSize: {320, 0}` problem is because of this. but don't know the reason — Payal Maniyar, May 11 '16 at 12:48
@PayalManiyar In **Storyboard->XIB->Attributes Inspector** and then uncheck **Adjust Scroll View Insets** — TheTiger, May 11 '16 at 13:21

Badal Shah · Answer 1 · 2016-05-11T13:02:58.970

I think you didn't set flow out correctly.

So, it will not go to - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath method . so, set break point and check each and every flow layout method.

Sequence call of flow layout method ,

1 st in viewdidload customflowlayout will be called like , //if you have set

 UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
    [flowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];
    float ratio = self.aCollectionView.frame.size.width/3;
    [flowLayout setItemSize:CGSizeMake(ratio, ratio)];
    [flowLayout setMinimumInteritemSpacing:0];
    [flowLayout setMinimumLineSpacing:0];

2nd , in your case this method also called

- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section

3rd - you need to check from this line , // you have set it correctly or not

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    float width = collectionView.frame.size.width/3;//120
    float height = collectionView.frame.size.height/4;//120
    return CGSizeMake(width-17,height-14);
}

4th , this method called

- (UIEdgeInsets)collectionView:
(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
    return UIEdgeInsetsMake(14.0, 14.0, 0.0, 14.0);
}

and last here cellforitem method is called . so, your this method not called so, problem is in above method try to set break point and change cell size and edge insect and etc and then try,

5th , if all above set correct then , below method called.

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath

score 0 · Answer 2 · edited May 23 '17 at 12:01

0

I had a similar issue a few years ago with my UITableView, and the solution was to drag'n'drop from my control to the parent view, in the Storyboard.

Just setting the values in my Objective-C code didn't seem to be enough...

Full details here:

Setting DataSource and delegate

edited May 23 '17 at 12:01

Community

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answered May 11 '16 at 12:41

Mike Gledhill

27,846
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score 0 · Accepted Answer · answered May 12 '16 at 07:02

0

[myCollectionView setContentInset:UIEdgeInsetsMake(100, 0, 0, 0)];

Above line solves my problem.

answered May 12 '16 at 07:02

Payal Maniyar

4,293
3
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cellForItemAtIndexPath is not called for collectionView

3 Answers3