pre select/highlight UICollectionViewCell on first load of view

Question

Im trying to preselect the first object/UICollectionViewCell in the UICollectionView? I have tried:

self.dateCollectionView.allowsMultipleSelection=NO;

[self.da         


        

Answer 1

For Swift 3.0.1 You can try this:

self.collectionView.selectItem(at: indexPath, animated: true, scrollPosition: [])

or

self.collectionView.selectItem(at: indexPath, animated: true, scrollPosition: UICollectionViewScrollPosition(rawValue: 0))

For Objective-C You can try this:

self.collectionView selectItemAtIndexPath:indexPath animated:YES scrollPosition:UICollectionViewScrollPositionNone];

Note: You should use it in viewDidAppear

Answer 2

I solved this by subclassing UICollectionView and selecting needed item in layoutSubviews:

class InitialSelectionCollectionView: UICollectionView {

   var initialSetupPerformed: Bool = false
   var initialSelectedIndexPath: IndexPath!

   override func layoutSubviews() {
       super.layoutSubviews()

       if !initialSetupPerformed && initialSelectedIndex != nil{
           selectItem(at: initialSelectedIndexPath, animated: false, scrollPosition: .centeredHorizontally)

           initialSetupPerformed = true
       }
   }
}

Then, when you init your custom collection view, just set needed IndexPath to initialSelectedIndexPath

Answer 3

For swift 3

Use collectionView.selectItem with-in this overload collectionView(UICollectionView, IndexPath)

This is my code, in this code I pre selected row with indexPath.row = 0

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = ScenarioCollectionView.dequeueReusableCell(withReuseIdentifier: "ReuseScenarioCollectionViewCell", for: indexPath as IndexPath) as! ScenarioCollectionViewCell

    if (indexPath.row == 0){
        collectionView.selectItem(at: indexPath, animated: true, scrollPosition: UICollectionViewScrollPosition.centeredHorizontally)
        cell.layer.borderColor=UIColor.gray.cgColor        
    }else{
        cell.layer.borderColor=UIColor.white.cgColor
    }
    return cell
}


func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.gray.cgColor
        }

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath as IndexPath)
    cell?.layer.borderColor = UIColor.white.cgColor
    collectionView.deselectItem(at: indexPath, animated: true)
}

Answer 4

For Swift 3:

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    //auto selected 1st item
    let indexPathForFirstRow = IndexPath(row: 0, section: 0)
    self.collectionView?.selectItem(at: indexPathForFirstRow, animated: true, scrollPosition: .top)
}

Answer 5

swift code for selecting a cell initially

func selectinitialCell() {

    let cell = venueTypeCollectionView.cellForItemAtIndexPath(NSIndexPath(forItem: 0, inSection: 0)) as! SearchTypeCollectionViewCell
    self.indexPathOfSelectedItem = NSIndexPath(forItem: 0, inSection: 0)
    cell.venueType.textColor = UIColor.whiteColor()
    cell.selected = true
}

but this does not invoke the delegate function such as didSelectItemAtIndexPath, didDeselectItemAtIndexPath.

Answer 6

    [self.collectionView reloadData];
    [self.collectionView layoutIfNeeded]; //important
    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:0];
    [self.collectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];
    [self collectionView:self.collectionView didSelectItemAtIndexPath:indexPath];