UICollectionReusableView method not being called

I want my sections in the UICollectionView to have a header with an image.

I have followed these steps:

• at the storyboard, assigned a header as an accessory for my UICollectionView
• gave it an identifier
• created a subclass of UICollectionReusableView for it
• assigned the custom class to the class at the storyboard.
• put an ImageView at the header accessory
• made an outlet for the ImageView at the custom class in the .h file
• Implemented the following at viewDidLoad:

 

[self.collectionView registerClass:[ScheduleHeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerIdentifier];

-(UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
	UICollectionReusableView *reusableview = nil;
	
	if (kind == UICollectionElementKindSectionHeader)
	{
		ScheduleHeaderView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerIdentifier forIndexPath:indexPath];
		
		headerView.headerImageView.image = [UIImage imageNamed:@"blah.png"];
		
		reusableview = headerView;
	}
	
	return reusableview;
}

I know that the datasource and delegate methods are working because I can see all the cells and its sections. However, I don't have my headers. I put in a breakpoint at the method above and it's never being called.

What am i doing wrong?

It seems that you have to give your header a non-zero size or collectionView:viewForSupplementaryElementOfKind:atIndexPath isn't called. So either set the headerReferenceSize property of the flow layout like so:

flowLayout.headerReferenceSize = CGSizeMake(self.collectionView.frame.size.width, 100.f);

Swift 5+

flowLayout.headerReferenceSize = CGSize(CGSize(width: self.collectionView.frame.size.width, height: 100))

or, implement collectionView:layout:referenceSizeForHeaderInSection if you want to vary the size by section.

You answered the question, but in words I understand better:

To make the method being called, add these methods:

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section {
	return CGSizeMake(60.0f, 30.0f);
}

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section {
	return CGSizeMake(60.0f, 30.0f);
}

...and go from there.

Swift 4 Xcode 9.1 Beta 2

Add @objc

@objc func collectionView(_ collectionView: UICollectionView, layout  collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize{
	let size = CGSize(width: 400, height: 50)
	return size
}

Credits: https://medium.com/@zonble/your-delegation-methods-might-not-be-called-in-swift-3-c6065ed7b4cd

Did you add UICollectionViewDelegateFlowLayout in current interface? This worked for me.

@interface MyViewController () <UICollectionViewDelegateFlowLayout>

Swift:

class MyViewController: UICollectionViewDelegateFlowLayout {

Swift 3.0 (xcode 8.2.1)

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
    return CGSize(width:collectionView.frame.size.width, height:30.0)
}

There is the swift version :

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
    let size = CGSize(width: 400, height: 50)
    return size
}

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
    let size = CGSize(width: 400, height: 50)
    return size
}

XCode (version 7.3.1 ) does not propose these methods in autocomplete !

If you just want a header, just keep the header method.

My problem was that in swift 3, the name of the viewForSupplementaryElementOfKind function has changed slightly from any posts that were on stack overflow. Hence, it was never getting called. Make sure that, if you're in swift 3, you're delegate function matches:

func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {}

    @objc (collectionView:viewForSupplementaryElementOfKind:atIndexPath:)
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView { }

The above code worked for me

I have the same issue. I have added referenceSizeForFooterInSection but then also viewForSupplementaryElementOfKind not getting called. I have added this code in viewDidLoad() and it worked for me:

if let flowLayout = self.collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
    flowLayout.sectionFootersPinToVisibleBounds = true   
}

Swift 5 Smooth and easy way

only these two line are missing in your code and you will done

use these line any where

let layout = self.colv.collectionViewLayout as! UICollectionViewFlowLayout
layout.headerReferenceSize = CGSize(width: self.colv.frame.size.width, height: 100)

I am using these lines in

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let CellCount = CGFloat(3.0)
    let width = CGFloat(collectionView.frame.size.width/CellCount)
    //let height = CGFloat(collectionView.frame.size.height)

    
    let layout = self.colv.collectionViewLayout as! UICollectionViewFlowLayout

    layout.headerReferenceSize = CGSize(width: self.colv.frame.size.width, height: 100)
    
    return CGSize(width: width, height: width+10)
}

For me, in Swift 4.2, func collectionView(collectionView:kind:indexPath:) -> UICollectionReusableView was never being called. This was for a collection view in a UIViewController. I noticed the existing collection view functions were qualified with @objc, and that the UICollectionView had not adopted the UICollectionViewDataSource and UICollectionViewDelegate protocols. As soon as I adopted the protocols, I got errors that the collection view functions did not match the protocol. I corrected the function syntax, removed the qualifiers, and the section headers started working.

If you've got a generic subclass then you must take care to specify ObjC delegate method name if it's different then Swift name (https://bugs.swift.org/browse/SR-2817).

@objc (collectionView:viewForSupplementaryElementOfKind:atIndexPath:)
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
...