Temporarily Hiding a cell in UICollectionView Swift iOS - ios

Question

I've been trying this for hours with no luck. I have a UICollectionView collectionView. The collection view is basically a list with the last cell always being a cell with a big plus sign to add another item. I've enabled reordering with the following. What I'd like for it to do is when I start the interactive movement, the plus sign cell goes away, and then when the user is done editing, it appears again. This is a basic version of the code I have:
func handleLongGesture(gesture: UILongPressGestureRecognizer) {
switch(gesture.state) {
case UIGestureRecognizerState.Began:
...
self.collectionView.beginInteractiveMovementForItemAtIndexPath(selectedIndexPath)
removeAddCell()
case UIGestureRecognizerState.Changed:
case UIGestureRecognizerState.Ended:
...
collectionView.endInteractiveMovement()
replaceAddCell()
default:
collectionView.cancelInteractiveMovement()
}
}
func removeAddCell(){
print("Reloading data - removing add cell")
data_source.popLast()
self.collectionView.reloadData()
}
func replaceAddCell(){
print("Reloading data - replacing add cell")
data_source.append("ADD BUTTON")
self.collectionView.reloadData()
}
It's very rough pseudocode, but I can't even get the simplest version of this to work. With the code I have, it gives me the dreaded "Fatal error: unexpectedly found nil while unwrapping an Optional values" on the line where I reference the UICollectionViewCell after removing the items from the data source.
If anyone who has done something like this could share their approach I'd really appreciate it! Thank you!
-Bryce

Answer 1

You can do something like this:
func longPressed(sender: UILongPressGestureRecognizer) {
let indexPath = NSIndexPath(forItem: items.count - 1, inSection: 0)
let cell = collectionView.cellForItemAtIndexPath(indexPath) as! YourCollectionViewCell
switch sender.state {
case .Began:
UIView.animateWithDuration(0.3, animations: {
cell.contentView.alpha = 0
})
case .Ended:
UIView.animateWithDuration(0.3, animations: {
cell.contentView.alpha = 1
})
default: break
}
}
this way it gradually disappears instead of abruptly.

Answer 2

I've done something like this. The data source for the collection view tracks a BOOL to determine whether or not to show the Add Item Cell. And call insertItemsAtIndexPaths: and deleteItemsAtIndexPaths: to animate the Add Item Cell appearing and disappearing. I actually use a Edit button to toggle the modes. But you can adapt this code to use your gesture recognizer.
basic code:
self.editing = !self.editing; // toggle editing mode, BOOL that collection view data source uses
NSIndexPath *indexPath = [self indexPathForAddItemCell];
if (!self.editing) { // editing mode over, show add item cell
if (indexPath) {
[self.collectionView insertItemsAtIndexPaths:#[indexPath]];
}
}
else { // editing mode started, delete add item cell
if (indexPath) {
[self.collectionView deleteItemsAtIndexPaths:#[indexPath]];
}
}