I need to get the next cell inside cellForItem within a collection view so that I can update a view object. When I try the following below it doesn't work. I've also tried indexPathForVisibleItems passing in indexPath.row + 1 and the produces an index out of range error.
let index = IndexPath(row: indexPath.row + 1, section: indexPath.section)
if let nextCell = collectionView.cellForItem(at: index) as! MKRCell {
nextCell.setupWaitView(time: timeToWait)
nextCell.waitViewHeightConstraint.constant = 80
nextCell.waitView.alpha = 1
nextCell.waitView.isHidden = false
}
Is this possible to achieve or will I need to do this via another way?
Thanks
No, it is not possible to get the cell object before initialization in cellForItemAt but here
you can receive the call before displaying the cell from UICollectionViewDelegate
func collectionView(_ collectionView: UICollectionView,willDisplay cell: UICollectionViewCell,forItemAt indexPath: IndexPath) {
if let myCell = cell as? MKRCell {
}
}
AND
If you want to set up the cell you have to setup view in the UICollectionViewDataSource
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
}
You should update the cell in:
func collectionView(_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
Remember to modify only the cell you'll be returning from this method. Other cells might not have exist at that moment.
Alternatively you can keep a weak reference to the cell and update it when needed.
Related
I have an odd problem with my UICollectionView. When I select the first cell in my Collection View the last cell is highlighted but does not show up in the array of selected index paths. Why is this happening?
Here is the code I am using to select and deselect the cells?
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
// handle tap events
print("You selected cell #\(indexPath.item)!")
let cell = collectionView.cellForItem(at: indexPath)
cell?.layer.borderWidth = highlightedCellBorderWidth
cell?.layer.borderColor = UIColor.yellow.cgColor
selectedImages.append(imageArray[indexPath.item])
print(selectedImages)
print(collectionView.indexPathsForSelectedItems)
}
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
let cell = collectionView.cellForItem(at: indexPath)
cell?.layer.borderWidth = 0
let index = selectedImages.index(of: imageArray[indexPath.item])
selectedImages.remove(at: index!)
print(selectedImages)
print(collectionView.indexPathsForSelectedItems)
}
You don't show how your cell is initialized, but...
collectionView(_:didDeselectItemAt:) is only called when the user successfully deselects an item. It does not get called if you deselect an item programmatically. If you are not resetting your layer's borderWidth when initializing a cell, the non-zero width will carry forward when the cell is reused by the collection view.
I found this link on S.O. which was helpful. To solve the problem I simply added the following code to my func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {}.
Code...
if collectionView.indexPathsForSelectedItems?.contains(indexPath) == true {
print("This cell is selected \(indexPath.item)")
cell?.layer.borderWidth = 3
cell?.layer.borderColor = UIColor.yellow.cgColor
}else{
cell?.layer.borderWidth = 0
}
I have more than one collectionView in a ViewController. The cell of those collectionViews has the same format.. so I'm reusing them. So my question is: How to identify in the method
func collectionView(_ collectionView: UICollectionView,
didSelectItemAt indexPath: IndexPath)
I don't want to do a couple of if's
I've found this solution everywhere, but really don't like it. Here is the code
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath)
if let aCell = cell as? ItemCollectionViewCell{
aCell.setupCell(with: self.items[indexPath.item])
}
return cell
}
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if collectionView == self.colletionViewTwo{
// goto viewController1
}else if collectionView == self.colletionViewOne{
// goto viewController2
}
}
Create two classes that implement the collection view delegate and data source and use one of each. So you'll have these two extra objects in your current view controller.
Seeing your code now, the above is probably too heavy. Alternatively, add a dictionary in which you store the collection view as key and a selector as value. This is extensible as you say you want.
To be honest, what's your issue an if (or switch) statement like you have now?
I have looked through google and stack overflow and I was not able to find an answer. I have a UICollectionView and would like to take the user to another view upon the cell being clicked. But before doing so I would like to click the cell on the simulator and have the label's name printed in the console so I can from there figure out how to write the performSegue method. I am having issues with the didSelectItemAt function.
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let clothesCell = collectionView.dequeueReusableCell(withReuseIdentifier: "clothesCell", for: indexPath) as! closetCollectionViewCell
clothesCell.clothingName.text = shirtStyle[indexPath.item]
clothesCell.clothingColor.text = shirtColor[indexPath.item]
clothesCell.clothingSize.text = "\(sizes[indexPath.item])"
return clothesCell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print(indexPath.item.clothingName)
}
Use this for print in didselectItem for selected items
print(shirtStyle[indexPath.item])
You need to get the cell that was clicked at indexPath like this:
let cell = collectionView.cellForItem(at:indexPath) as! closetCollectionViewCell
Then just get the values from the cell variables and print.
I want to set a variable to different string when a certain CollectionView cell is tapped. So cell1 is tapped then var cellTapped = "cell1", cell 2 is tapped then var cellTapped = "cell2" and so on. It was suggested that I
"create a custom cell and hold the value as property and read this
value on didSelectCell()"
but I'm not sure how to do this (newbie).
(Swift 3)
You need to set UICollectionViewDelegate to your ViewController and then implement didSelectItemAt IndexPath that gets called when a cell is tapped.
Something like this:
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
cellTapped = "cell" + String(indexPath.row)
}
You could also have an array of Strings and index into the array based on the indexPath.row:
let cellStringValues = ["cell1", "cell2", "cell3", ... , "celln"]
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
cellTapped = cellStringValues[indexPath.row]
}
Setup your view controller to be the delegate of the UICollectionView. Your view controller should inherit from UICollectionViewDelegate. Then in the viewDidLoad() for the VC set the delegate variable for the UICollectionView to be the ViewController. To catch selection events override the following UICollectionViewDelegate function.
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
cellTapped = "cell\(indexPath.row)"
}
Check out https://www.raywenderlich.com/136159/uicollectionview-tutorial-getting-started for more details on working with collection views
I have created a collection view that pulls from an array of images (8 right now, but user can add more). I originally was using a scrollview, but found it easier with a collection, and thanks to this great community, went to a collection view. I need to find the indexPath to delete an item at a given point. So here is some code I have so far, but I am new to this specifically. Here is some code I currently have.
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
#IBOutlet weak var myCollectionView: UICollectionView!
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return imageArray.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! UserFeedCollectionViewCell
cell.myImage.image = UIImage(named: imageArray[indexPath.row])
cell.myImage.layer.cornerRadius = 12.0
cell.myImage.clipsToBounds = true
return cell
}
//delete item at current item - 2
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if indexPath.row > 2 {
myCollectionView.deleteItems(at: [])
}
}
Hope this will help and feel free to ask in the comments if you have a question.
Edit: Paging is enabled, and it is horizontal scrolling, and each image takes up the whole cell.
How about keeping an array of tapped on image indices?
Define a variable for the indexes at the top:
var selected = [IndexPath]()
Then implement didSelectItemAt as:
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
selected.append(indexPath)
if selected.count > 2 {
let ndx = selecte.count - 3
let twoBack = selected[ndx]
myCollectionView.deleteItems(at:[twoBack])
}
}
The above would work fine for the first selection, but at that point, you would need to figure out how you handle the next selection - whether you wipe the selected array and start over, or need to keep track of further selections to handle the next input.
Depending on how you want to proceed, the selected array would either need to be wiped or to be modified to remove the item that was deleted.