I want to disable delete and move the 1st cell in UICollectionView. And also other cells in UICollectionView cannot move to the 1st one. How to implement it？
To disable movement you need to implement UICollectionViewDataSource protocol and use this method:
func collectionView(_ collectionView: UICollectionView, canMoveItemAt indexPath: IndexPath) -> Bool {
return indexPath.item != 0
}
Disabling deletion depends totally on your deletion implementation.
Related
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?
new to swift. I have a nested CollectionView from one viewcontroller. The main viewcontroller has 7 collectionviewcell ("Level1Cell" in the code below). Each time I click a button or trigger an event, I want the collectionView to reload with the new data.
func eventHandler() {
// updates data
myCollectionView.reloadData()
}
Then, after it calls reload, it will call the reload again on each of the the nested CollectionViewCell.
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Level1Cell", for: indexPath) as! Level1Cell
cell.appsCollectionView.reloadData()
return cell
}
The problem is, let say I want to, for the first cell, set a particular row some text.
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if(self.index == 0 && indexPath.row == 30){
rightCell.textLabel.text = "asdasd"
}
The fourth "Level1Cell" cell somehow has its label set also at the 30th row, but not the second and third. After stepping through the debugger, I realize that the cells, after reloading, the fourth cell "Level1Cell" is set to have the the same memory address as the first cell ( why does reload do this - shouldn't it allocate a new memory for each "Level1Cell"? - how can I get around this). Also, should I not use reload to update the data in the view and nested view of those from the view controller?
Thanks!
UIcollectionview will reuse cells. You must provide needed data for row in method
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
Or just clear previous data at cell.
What is the most common way to delete cells from a UICollectionView?
In a UITableView I use the editActionsForRowAt or editingStyle methods to delete rows, does UIControllerView has something similar or you need to implement your own deleting method?
What I have is a UICollectionView with a lot of photos where each cell/photo is attached to a segue which takes you to a larger version of the photo.
The easiest way I could be to do it in the didSelectItemAt method but in my case that is not an option since as soon as a photo is tapped it segues to the other viewController (larger image).
What would be the best way to add a deleting functionality in a situation like the one I'm describing above?
The following threads show how to delete using the didSelectItemAt.
How to add a delete button to Collection View Cell in Swift?
How to delete item from collection view?
CODE
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return fruits.count
}
public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "fruitCustomCell", for: indexPath) as! fruitCollectionViewCell
cell.labelFruitName.text = fruits[indexPath.row].fruitName
return cell
}
App Diagram
I am working on a grid based game (like minesweeper). It is a 2d grid that I am displaying using a UICollectionView that contains a set of custom UICollectionViewCell cells.
I want to be able to listen to touch events on individual cells. Is it fine to add an UITapGestureRecognizer() to each of the cells (on a 20x20 board, for example). Or is there a better way?
I understand from Ahmad's reply that using this works for single taps:
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print(indexPath.row)
}
However, I want different event handlers for single vs double taps on the cells.
If you want to let the base container as a UICollectionView (which I find it a good idea), I doubt that you need to add UITapGestureRecognizer to it, all you have to do is to let your class (Controller) to conforms to UICollectionViewDelegate its Delegate and implement collectionView:didSelectItemAtIndexPath:.
Also, the benefit that you'll get when implementing this method is you can easily determine which cell has been selected, by checking what is the indexPath.row of the selected cell, as follows:
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print(indexPath.row)
}
Don't forget to:
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource { //...
EDIT:
In case of you want to add a double tap functionality to your collection view, I suggest to check this answer to achieve it.
Hope this helped.
I have UICollectionView and the selected cell should like the yellow one in pic. So how to have a separate design for the selected cell and how to draw that curve above it ?
Shall I use 2 separate UICollectionViewCell for this ? Or there is any alternate way to reuse the same cell on selection.
Shall I use 2 separate UICollectionViewCell for this ?
That's one way to go. Do this if there are more differences than just the one you described.
Or there is any alternate way to reuse the same cell on selection.
Sure, you can do that. Look at the two cells in your illustration, but consider that the grey part above each one as part of the cell. The black rectangle and yellow bulging rectangle are simply two different images that you draw in the background of the cell, and you can configure the same type of cell either way simply by changing that image. This is a good approach if other aspects of the cell, like positions of labels and such, are the same between both cells.
If this is the only different between that you want to make after selection, I think that there is no need to create two different UICollectionViewCells, instead, you need to keep a reference on indexpath.row(s) of selected cell(s) and check if this is the selected row, change/add a new background image.
For example:
class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
// here is the variable that should save the current selected row...
private var selectedRow: Int?
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
// let's consider that you have a custom cell called "MyCustomCell"
// which has "backgroundImage" property...
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "myCellID", for: indexPath) as! MyCustomCell
// checking based on the selected row
cell.backgroundImage = indexPath.row == selectedRow ? UIImage("yellow") : UIImage("default")
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
selectedRow = indexPath.row
collectionView.reloadData()
}
}
Note that if you want to check on more than one row, you should declare a selectedRows as an array (or maybe as a set) of Ints.
Hope it helps.