UICollectionView - Select first cell as View Will Appear

Question

In my collection view I need to select the first cell as soon as the view appear.

I have implemented didSelectItemAtIndexPath and didDeselectItemAtIndexPath When the cell is selected it shows a green border when is not selected the cell has a white border.

What I need to have is to start my app with the first cell with a green border.

I have tried to use selectItemAtIndexPath however, the first cell is not showing the green border. What am I missing?

override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)

        let firstIndexPath = NSIndexPath(forItem: 0, inSection: 0)

        frameCollectionView.selectItemAtIndexPath(firstIndexPath, animated: false, scrollPosition: .None)

    }

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {

        let frameCell = collectionView.cellForItemAtIndexPath(indexPath) as! FrameViewCell

        frameCell.layer.borderWidth = 2
        frameCell.layer.borderColor = UIColor.greenColor().CGColor
    }

    func collectionView(collectionView: UICollectionView, didDeselectItemAtIndexPath indexPath: NSIndexPath) {

        let frameCell = collectionView.cellForItemAtIndexPath(indexPath) as! FrameViewCell

        frameCell.layer.borderWidth = 1
        frameCell.layer.borderColor = UIColor.whiteColor().CGColor
    }

At that point the cells are not loaded yet so you cannot select one. — Sulthan, Apr 01 '16 at 22:10
I have also tried to add a delay of 5 seconds before the selection is called. But the cell is still not selected — SNos, Apr 01 '16 at 22:18

score 1 · Answer 1 · edited May 23 '17 at 10:30

1

The delegate method are not called when you are selecting/deselecting programatically. They are called only if the user selects/deselects.

A better way is to change UI inside the cell class, see for example Trying to override "selected" in UICollectionViewCell Swift for custom selection state

edited May 23 '17 at 10:30

Community

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answered Apr 01 '16 at 22:22

Sulthan

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thank you! I have already looked at that answer however, it will select the cell only when scrolled and not when the view loads – SNos Apr 01 '16 at 22:37
@SNos When a cell loads, it is not selected. – Sulthan Apr 01 '16 at 22:39
Ok but there is a way to get only the first cell on view load with a green border? – SNos Apr 01 '16 at 22:42
`self.frameCollectionView.delegate?.collectionView!(self.frameCollectionView, didSelectItemAtIndexPath: NSIndexPath(forItem: 0, inSection: 0))` will select the cell however, when select another cell the first one is not deselected – SNos Apr 01 '16 at 23:01

score 1 · Accepted Answer · answered Apr 01 '16 at 23:50

Found the solution. In viewDidLoad():

utilityClass.delay(0.1) {
            let indexPathForFirstRow = NSIndexPath(forItem: 0, inSection: 0)
            self.frameCollectionView.selectItemAtIndexPath(indexPathForFirstRow, animated: false, scrollPosition: .None)
            self.collectionView(self.frameCollectionView, didSelectItemAtIndexPath: indexPathForFirstRow)
        }

UICollectionView - Select first cell as View Will Appear

2 Answers2