didHighlightItemAtIndexPath not working as expected

Question

In regards to a UICollectionViewDelegate I'm using didHighlightItemAtIndexPath as well as didSelectItemAtIndexPath

didSelectItemAtIndexPath is working as expected. That is, when I click the remote, this code runs.

The issue is that didHighlightItemAtIndexPath is running on click as well, when the name suggests this block will only run on highlight. Am I missing something?

The respective blocks:

func collectionView(collectionView: UICollectionView, didHighlightItemAtIndexPath indexPath: NSIndexPath) {
    let node: XMLIndexer = self.xml!["ArrayOfVideo"]["Video"][indexPath.row]

    let title = (node["Title"].element?.text)!
    let date = (node["Date"].element?.text)!(node["SpeakerOrganization"].element?.text)!

    self._title.text = title
    self._date.text = date
}

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    let node: XMLIndexer = self.xml!["ArrayOfVideo"]["Video"][indexPath.row]

    let videoUrl = (node["VideoURL"].element?.text)!

    self.playVideoByUrlString(videoUrl)
}

Extra Notes

For the UICollectionViewCell I'm getting the parallax feel on the cell's image by adding the following:

// self is a UICollectionViewCell
// self.imageView is a UIImageView

self.imageView.adjustsImageWhenAncestorFocused = true
self.imageView.clipsToBounds = false

Solution

Override shouldUpdateFocusInContext in your UICollectionView's delegate

Answer 1

Method didHighlightItemAtIndexPath called before didSelectItemAtIndexPath because of UICollectionView arrangement. Every time you touch cell it highlighted before you select it (for visual purpose I assume). You can see it with this example:

func collectionView(collectionView: UICollectionView, didHighlightItemAtIndexPath indexPath: NSIndexPath) {
    print("highlight")
}

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    print("select")
}

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath)
    let imageView = UIImageView(frame: CGRect(origin: CGPointZero, size: cell.frame.size))
    imageView.image = imageFromColor(UIColor.redColor(), size: cell.frame.size)
    imageView.highlightedImage = imageFromColor(UIColor.blueColor(), size: cell.frame.size)
    cell.addSubview(imageView)
    return cell
}

func imageFromColor(color: UIColor, size: CGSize) -> UIImage {
    let rect = CGRectMake(0, 0, size.width, size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
}

When I touch cell output is

highlight 
select

If you want your cell be highlighted or selected only take a look at UICollectionViewDelegate's methods shouldHighlightItemAtIndexPath, shouldSelectItemAtIndexPath. You can prevent selecting of highlighted cell by checking it's indexPath inside shouldSelectItemAtIndexPath.