I want to change the colour of a UILabel inside a UICollectionViewCell when the device orientation changes. How can I achieve this.
NotificationCenter.default.addObserver(self, selector: #selector(deviceOrientationDidChange),
name: NSNotification.Name.UIDeviceOrientationDidChange, object: nil)
I wanted to observer orientation changed notification inside of the cell but i though it's not right, because there would be no way to remove the observer. The question is if I observe orientation changes in view controller, how do I get a reference to the UICollectionView cells inside the notification selector to change the cell's label textColor? This is what I was tried to use:
let indexPath = IndexPath(item: 0, section: 0)
if let cell = collectionView.cellForItem(at: indexPath) as? CommentCell {
cell.displayNameLabel.textColor = .white
cell.commentLabel.textColor = .white
}
but i can only access one cell view that indexPath. When I set an Int variable and set it value inside cellForRowAtIndexPath, nothing happens because it holds the value of the last item.
Put this in cellForRowAt
if(orinatedLogic)
{
cell.displayNameLabel.textColor = .white
cell.commentLabel.textColor = .white
}
else
{
cell.displayNameLabel.textColor = .blue
cell.commentLabel.textColor = .blue
}
and reload the collection whenever orientation changed
There is lot of possibilities depends on you requirements. I assume you don't want to reload entire collection view. But you can enumerate all visible cells and either reload them,
collectionView.reloadItems(at: collectionView.indexPathsForVisibleItems)
or change them directly.
collectionView.visibleCells.flatMap{ $0 as? CommentCell}.forEach {
$0.commentLabel.textColor = ...
}
For Orientation change you can simply add
override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
super.viewWillTransition(to: size, with: coordinator)
collectionView.reloadItems(at: collectionView.indexPathsForVisibleItems)
}
In your collection view cell for item
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "item", for: indexPath) as! YourCellType
cell.displayNameLabel.textColor = UIDevice.current.orientation.isPortrait ? .white : .red
cell.commentLabel.textColor = UIDevice.current.orientation.isPortrait ? .white : .red
}
That's It , You did it !!
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