UICollectionView: header view programmatically

Question

This is the way i am working on header.

  //    viewDidLoad

  [self.collectionView registerClass:[UICollectionViewCell class]forCellWithReuseIdentifier:@"Cell"];

[self.collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];

UICollectionViewFlowLayout *layout= [[UICollectionViewFlowLayout alloc]init];

self.collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, 390, 300) collectionViewLayout:layout];
layout.collectionView.backgroundColor = [UIColor colorWithRed:230.0/255.0 green:230.0/255.0 blue:230.0/255.0 alpha:1.0];
[self.collectionView registerClass:[UICollectionViewCell class]
        forCellWithReuseIdentifier:@"Cell"];
self.collectionView.delegate=self;
self.collectionView.dataSource=self;
layout.minimumInteritemSpacing = 15;

[layout setScrollDirection:UICollectionViewScrollDirectionVertical];

self.collectionView.collectionViewLayout = layout;
self.collectionView.showsHorizontalScrollIndicator = NO;
self.collectionView.showsVerticalScrollIndicator = NO;
[self.collectionView setBounces:YES];
self.collectionView.allowsMultipleSelection = YES;
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"HorizontalPickerCell"];
[self.view addSubview:self.collectionView];

   - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
  {
  if (section == 0) {
    return CGSizeMake(0, kHeaderHeight);
  }
  return CGSizeMake(0, kHeaderHeight + kInterSectionMargin);
  }

  - (NSInteger)numberOfSectionsInCollectionView: (UICollectionView *)collectionView
  {
NSLog(@"levels count:%d", [arrLevels count]);
return [arrLevels count];
  }

  - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 {
 NSLog(@"vals count:%d", [arrSeats count]);
 for(int i=0; i<[arrLevels count]; i++)
 {
    if(section == i)
    {
        int c;
        NSString *cnt = [NSString stringWithFormat:@"%@",[arrTot objectAtIndex:i]];
        c = [cnt intValue];
        return c;
    }
 }
 return 1;
 }

 - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [self.collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];

//cell.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"blue_s.png"]];

if (cell.selected) {
    [UIColor colorWithPatternImage:[UIImage imageNamed:@"blue_s.png"]]; // highlight selection
 }
else
 {
    cell.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"yellow_seat.png"]]; // Default color
 }

return cell;
 }

 - (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
return UIEdgeInsetsMake(10, 12, 10, 10);
 }

 - (CGSize)collectionView:(UICollectionView *)collectionView layout:  (UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
CGSize retval =  CGSizeMake(22, 20);
return retval;
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
UICollectionReusableView *reusableview = nil;

if (kind == UICollectionElementKindSectionHeader) {
    UICollectionReusableView *headerView = [self.collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:nil forIndexPath:indexPath];

        self.lblHeader = [[UILabel alloc]initWithFrame:CGRectMake(120, 10, 100, 30)];
        self.lblHeader.backgroundColor = [UIColor whiteColor];
        self.lblHeader.textColor = [UIColor redColor];
        self.lblHeader.text = @"Level 1";
        [self.collectionView addSubview:self.lblHeader];
}
return reusableview;
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
printf("Selected View index=%d",indexPath.row);

itemPaths  = [self.collectionView indexPathsForSelectedItems];

UICollectionViewCell* cell=[self.collectionView cellForItemAtIndexPath:indexPath];
cell.contentView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"blue_s.png"]];
 }

 - (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath
 {
UICollectionViewCell* cell=[self.collectionView cellForItemAtIndexPath:indexPath];
cell.contentView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"yellow_seat.png"]];
 }

CEarwood · Accepted Answer · 2013-05-22 05:37:55Z

The error you're seeing is pretty clear. You're trying to dequeue a reusable view but the collection view doesn't know anything about the reuse identifier you're passing.

You need to call registerClass:forSupplementaryViewOfKind:withReuseIdentifier: before dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath: is called. I typically call one of the register methods in viewDidLoad so all the setup is done and I can just call the dequeue method. If you're loading your custom header and footer views from nib you can use the registerNib:forSupplementaryViewOfKind:withReuseIdentifier: method.

Edit

I see you updated the code. You need to move these lines

UICollectionViewFlowLayout *layout= [[UICollectionViewFlowLayout alloc]init];

self.collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, 390, 300) collectionViewLayout:layout];

above the lines where you're calling the register class methods. You cannot send messages to an object before you allocate and initialize it.

That thing is done already please check in question last line.
Yes, you're calling it in the last line. It needs to be called BEFORE you call dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath: registerClass:forSupplementaryViewOfKind:withReuseIdentifier: shouldn't be called from this method anyway. Move it to viewDidLoad or wherever you're configuring the view
Also the error you posted references "Test Header View" which, I'm assuming is coming from the other answer? Make sure you're reuseIdentifier's are the same. That's how the collectionview knows what type of reusable view you're dequeing.
No, that's not the issue, that was my posting mistake. i edited the question.
As I said that error's very clear. You aren't registering the class before calling the dequeue method. Without seeing more of your code I can't tell you where the error is. I'm unable to duplicate your issue after copying and pasting the updated code from this question. You now have 3 answers and all 3 are correct given the information we have.

SAMIR RATHOD · Answer 2 · 2013-05-17 11:32:08Z

try this :

    //ON top 
    static NSString *headerViewIdentifier = @"Test Header View";
    static NSString *footerViewIdentifier = @"Test Footer View";


    - (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
    {
        NSString *identifier = nil;

        if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
            identifier = headerViewIdentifier;
        }
        else if ([kind isEqualToString:UICollectionElementKindSectionFooter]) {
            identifier = footerViewIdentifier;
        }

        // TODO Setup view

        UICollectionReusableView *supplementaryView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:identifier forIndexPath:indexPath];

        return supplementaryView;
    }

but you haven't registered the class, it is giving this error.

Aditya Nagrath · Answer 3 · 2013-05-22 04:17:56Z

Typically you put this register line in the viewDidLoad or some sort of initialize so that it is not called over and over again. But mainly you have some confusion. You register a class for the header but you dequeue a class on the footer. You should register a class for both and dequeue the right one for each.

Notice your register uses UICollectionElementKindSectionHeader:

[self.collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];

Notice your dequeue uses UICollectionElementKindSectionFooter :

UICollectionReusableView *supplementaryView = [self.collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"header" forIndexPath:indexPath];

hope that helps.

No, that's not the issue, that was my posting mistake. i edited the question.
What is your current error? That was removed from the question.
Is it just not showing up? You told it the width of the cell is 0 if I am not mistaken.

Hercules · Answer 4 · 2013-05-22 05:18:00Z

If you are not displaying anything on the header then how could you expect header view to show you something on header part of UICollectionView.Try following code.This is working code

- (void)viewDidLoad
{
    arry=[[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four", nil];
    [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cellIdentifier"];
    [self.collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView"];

    // Do any additional setup after loading the view, typically from a nib.
}


    - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return [arry count];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 20;
}

// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath];

    if (cell==nil) {
        cell=[[UICollectionViewCell alloc] init];
    }
    UILabel *label=[[UILabel alloc] initWithFrame:CGRectMake(0, 0, 60, 60)];
    label.text=[arry objectAtIndex:indexPath.row];
    [cell.contentView addSubview:label];

    NSLog(@"cell is %@",NSStringFromCGRect(cell.frame));
    return cell;
}


- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    return CGSizeMake(60, 60);
}

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    UIEdgeInsets insets=UIEdgeInsetsMake(10, 10, 10, 10);
    return insets;
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    if (kind == UICollectionElementKindSectionHeader) {

        UICollectionReusableView *reusableview = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView" forIndexPath:indexPath];

        if (reusableview==nil) {
            reusableview=[[UICollectionReusableView alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
        }

        UILabel *label=[[UILabel alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
        label.text=[NSString stringWithFormat:@"Recipe Group #%i", indexPath.section + 1];
        [reusableview addSubview:label];
        return reusableview;
    }
    return nil;
}

Hercules · Answer 5 · 2013-05-22 05:37:49Z

why are you adding lblHeader to self.collectionView add to headerView.And return headerView.Replace your code with it

    if (kind == UICollectionElementKindSectionHeader) {
    UICollectionReusableView *headerView = [self.collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:nil forIndexPath:indexPath];

        self.lblHeader = [[UILabel alloc]initWithFrame:CGRectMake(120, 10, 100, 30)];
        self.lblHeader.backgroundColor = [UIColor whiteColor];
        self.lblHeader.textColor = [UIColor redColor];
        self.lblHeader.text = @"Level 1";

       // [self.collectionView addSubview:self.lblHeader];
          [headerView addSubview:self.lblHeader];

       return headerView;
}

asked	19 days ago
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active	14 days ago

UICollectionView: header view programmatically

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