I've created a simple app and dragged a UICollectionView onto it. There is one cell, I've given it an ID of cell and added a label to it. I've also changed the background color of the collectionview and the cell.
When I run the app in the simulator the collectionview is there but the cell is not.
I have no Idea what i'm doing wrong an i'm starting to get really pissed off.
class ViewController: UIViewController, APExpandingTextViewDelegate,UICollectionViewDataSource,UICollectionViewDelegate {
...
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 1;
}
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath) as! UICollectionViewCell
return cell;
}
Nothing ever shows up.
screen shot of the IB
Check datasource and delegate of collection view are connected or not in storyboard.
Related
I have a big problem.
I scrolled in the UICollectionView.
When the drawing area is scrolled too much, the arrangement order has become disjointed.
I do not want to change the order even though scrolling.
What should I do?
help me.
let titles = ["1","2","3","4","5","6","7","8", "9", "10", "11", "12"] //titles
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 12
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = testCollectionView.dequeueReusableCell(withReuseIdentifier: "TestCell", for: indexPath) as! TestCell //customCell
let testTitle = cell.contentView.viewWithTag(2) as! UILabel
testTitle.text = titles[indexPath.row]
return cell // yeah, all done. is these code is normal. right? But when i scroll this UICollection, change the order in Outside drawing area.
}
You should definitely not be using viewWithTag. The reason for this is because cells are dequeued, which means that cells that have been taken off screen by scrolling are reused for the cells which are about to come on screen. This is done to save memory. Sometimes the problem with the order can be because previously used cells are not updated quick enough when they are presented to the user. The solution to this if you are using a network request can be to firstly to streamline your request and then cache any heavy data that is returned, such as images.
Your code should not be causing the cells to change order. I'm wondering if you have a problem with using viewWithTag. That's a fairly fragile way to find views in a collection view/table view cell.
You already have a custom cell type. I would suggest creating an outlet to your label in your custom cell type, and referencing the label that way:
class TestCell: UICollectionViewCell {
//(Connect this outlet in your cell prototype in your Storyboard
#IBOutlet titleLabel: UILabel!
}
//And in your view controller's cellForItemAt method...
cell.titleLabel.text = titles[indexPath.row]
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.
I am trying to create simple educational app about movies, and I need to create movie frames horizontal scroller.
I create collection view for that:
But if I build it for another target (iPhone 6s Plus for example), I have this:
How to solve this problem?
My scene controller code (Swift 3):
public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 4
}
public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
cell.backgroundColor = UIColor.black
// Configure the cell
return cell
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
I think that you can try to implement the method of UICollectionView delegate:
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
return CGSizeMake(yourHeight, self.view.frame.size.width)
}
in this way, your collectionView-cell inside in tableView will appear as big as the screen.
First I want to say something about UITableViewAutomaticDimension you use, in case you not exactly understand how it works.
Your expectations probably are, that UITableViewAutomaticDimension will infer tableView to make a cell with size of entire tableView, but it doesn't work this way.
UITableViewAutomaticDimension is just infers tableView, that inner size of your cell will be used as a returned here; so if you add some constraints, views with constraints, or whatever inside your tV, its size will be used.
and second - your comment doesn't make sense at all for me, because your posted code isn't related to cell of collectionView and I can't comment anything related to size of its cells
EDITED:
to make all cells with width of your screen, return correct size from delegate method of collectionViewFlowLayout - sizeForItem
I created a Collection View using purely the storyboard interface builder. This is what the storyboard looks like:
My collection view's properties are default as well. I haven't written anything into my ViewController.swift yet.
For some reason, when I run on my phone / emulator, none of the buttons are showing.
UICollectionView does not support static cells like UITableView. You will have to set its dataSource,delegate and configure your cells in code.
Just configure the collectionView properly see below code and image:
Implement the delegate methods of collectionView:
class yourClassController: UICollectionViewDataSource, UICollectionViewDelegate {
override func numberOfSectionsInCollectionView(collectionView:
UICollectionView!) -> Int {
return 1
}
override func collectionView(collectionView: UICollectionView!,
numberOfItemsInSection section: Int) -> Int {
return yourArray.count
}
override func collectionView(collectionView: UICollectionView!,
cellForItemAtIndexPath indexPath: NSIndexPath!) ->
UICollectionViewCell! {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("CollectionViewCell", forIndexPath: indexPath) as CollectionViewCell
// Configure the cell
cell.backgroundColor = UIColor.blackColor()
cell.textLabel?.text = "\(indexPath.section):\(indexPath.row)"
cell.imageView?.image = UIImage(named: "circle")
return cell
}
Then from your storyboard set the delegate and datasource by drag and drop see image:
Note: collectionView appears when you do complete above formality with its relevant class.
I have a weird issue with UICollectionView and UITabBarController. Inside the UITabBarController i have references to two different ViewControllers. If i put View Controller that has UICollectionView as a first page of UITabBarController then my list with cells (UICollectionView) is loading normally like this:
But if i put it as a second View Controller when i open the tab it is like UIImageView and UILabel are disappearing from the cells:
I have checked collectionView method that is getting the cells and there is always data printed for the Label and Image. Here is a code of the methods for DataSource and Delagate
// tell the collection view how many cells to make
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.items.count
}
// make a cell for each cell index path
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
// get a reference to our storyboard cell
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! AdsCollectionViewCell
// Use the outlet in our custom class to get a reference to the UILabel in the cell
cell.myLabel.text = self.items[indexPath.item]
cell.backgroundColor = UIColor.whiteColor() // make cell more visible in our
cell.layer.borderColor = UIColor.grayColor().CGColor
cell.layer.borderWidth = 1
cell.layer.cornerRadius = 8
cell.layoutIfNeeded()
return cell
}
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
let width = collectionView.frame.width - 22;
return CGSize(width: width/2, height: width/2);
}
// MARK: - UICollectionViewDelegate protocol
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
// handle tap events
print("You selected cell #\(indexPath.item)!")
}
Is there someone that had problem like this? How can it be solved?