So I have collection view with 3 cells, each of which has a tableview in it. Obviously, each collection view cell has to load it's table view with different data for the table view cells.
My first thought was to make the collection view the delegate and datasrouce of the table view, but even so, the datasource will need to know which collection view cell is being loaded.
Also thought of making a separate class for the DS and delegate for both the collection view and the table view, but then again, I'm stuck on how the tableview DS will know which collection view cell it's being loaded from.
Any thoughts?
EDIT:
After I make the assignment, the datasource field is nil. So what am I missing here?
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) else {
return UICollectionViewCell.init()
}
cell.backgroundColor = UIColor.clear
cell.theTableView.dataSource = RequestedTableDataSource.init()
cell.theTableView.delegate = self
cell.theTableView.reloadData()
return cell
}
class RequestedTableDataSource: NSObject, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 16
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
guard let cell = tableView.dequeueReusableCell(withIdentifier: "RequestedCell") as? IntervieologistRequestedCell else {
return UITableViewCell.init()
}
cell.setupCellFor(name: "Dan", image: UIImage.init(named: "dan")!)
return cell
}
}
If I do this:
let foo = RequestedTableDataSource.init()
cell.myTableView.dataSource = foo
then the dataSource field is set, numberOfRows gets called, but cellForRowAtIndexPath doesn't.
You can set the tableView.tag to an unique integer and identify it later in the delegate methods using that, but I would recommend keeping a seperate datasource/delegate for each tableview, much cleaner.
Don't make the CollectionView or any other View object the datasource/delegate.
eg set
collectionViewCell.tableView.tag = index;
collectionViewCell.tableView.delegate = commonDelegate;
or
collectionViewCell.tableView.delegate = uniqueDelegate; // Better choice
Related
My code has a UICollectionView inside a UITableViewCell. I have two different set of arrays named TopBrandArray & TopCategoryArray - which is being displayed in two different cells of a Table inside a collectionView.
The delegates and datasource has been connected to the HomeViewController in the main storyboard. Also, the name for the cells has been given.
There is no error while compiling the program but gets an expection while running the code.
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'could not dequeue a view of kind: UICollectionElementKindCell with identifier TopCategoryCollectionID - must register a nib or a class for the identifier or connect a prototype cell in a storyboard
When I am trying to run by displaying only one single cell of the tableviewcell, the code works fine. But if am adding more cell the above mentioned error pops up. Here,I am adding the code:
#IBOutlet weak var homePageTable: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
self.homePageTable.reloadData()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 2
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if indexPath.row == 0{
let cell = tableView.dequeueReusableCell(withIdentifier: "TopCategoryID", for: indexPath) as! TopCategoriesTableViewCell
cell.tablecollection1.reloadData()
return cell
}
else{
let cell = tableView.dequeueReusableCell(withIdentifier: "BrandTableID", for: indexPath) as! BrandsTableViewCell
return cell
}
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 162
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if section == 0{
return topCategoryArray.count
}
else{
return topBrandArray.count
}
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "TopCategoryCollectionID", for: indexPath) as? TopCategoriesCollectionViewCell{
cell.cat_image.image = UIImage(named: topCategoryArray[indexPath.row].image)
print(topCategoryArray[indexPath.row].name)
cell.cat_value.text = topCategoryArray[indexPath.row].name
return cell
}
else{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "BrandsCollectionID", for: indexPath) as! BrandsCollectionViewCell
cell.layer.borderWidth = 1.5
cell.layer.borderColor = UIColor.gray.cgColor
cell.layer.cornerRadius = 4
cell.brandimage.image = UIImage(named: topBrandArray[indexPath.row].image)
return cell
}
}
}
Since it is asking to register a nib or a class for the identifier, I do not know where inside the code should I write the code because when I wrote it in viewDidload(), an error popped up showing "Ambiguous reference to member collectionView(_:numberOfItemsInSection:)"
The issue is with the registration of the cell with collection view. The collection view is unable to dequeue cell with the "TopCategoryCollectionID" identifier. You need to say to collection view that I'm going to use this cell as collection view cell.
You need to register TopCategoryCollectionID cell to collection view.
let nib = UINib(nibName: "TopCategoryCollectionID", bundle: nil)
collectionView.register(nib, forCellWithReuseIdentifier: "TopCategoryCollectionID")
If you have used cell in storyboard then no need to register cell again.
EDIT
As you have collection view inside your tableview cell so datasource and delegate of collection view must be implemented indie the respective cells.
You need to transfer the collection view code into table view cells.
I am creating a scrollable view filled with monthly calendars. I'm using a collection view to display a calendar inside a table view full of calendars. So each table view cell is a calendar for a specific month, and each collection view cell is a day. I have a separate swift file for the tableview cell from the view controller. Since each tableview cell is going to look different (because different months), the tableview cell needs to know which row it is placed in inside the tableview during its creation in dequeque cell function.
tableView.dequeueReusableCell(withIdentifier: "CalendarTableViewCell", for: indexPath)
I need to get the indexPath in the "for: indexPath" parameter inside the tableview cell file because the collectionview inside the tableview cell gets created when the tableview cell is dequeued. The contents of the collection view depends on which tableview row it's in. So how do I get that parameter?
Sorry for the long explanation, please help if possible. Thank you!
Create an array in UITableViewCell subclass and use that array in collection view data source methods.
class MonthCell: UITableViewCell, UICollectionViewDelegate, UICollectionViewDataSource {
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
let datesArray = [String]()
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return datesArray.count
}
}
In tableView cellForRowAt method assign the date values and reload the collectionView
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "CustomCell") as! MonthCell
cell.datesArray = []//dates based on indexPath
cell.collectionView.reloadData()
return cell
}
Or
Assign a reference to the table view cell index path in tableView cellForRowAt method
class MonthCell: UITableViewCell, UICollectionViewDelegate, UICollectionViewDataSource {
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
var tableIndexPath:IndexPath?
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if let tableIndexPath {
// return value based on tableIndexPath
} else {
return 0
}
}
}
//cellForRowAt
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "MonthCell") as! MonthCell
cell.tableIndexPath = indexPath
cell.collectionView.reloadData()
return cell
}
i have a uiviewcontroller, where i put a uitableview, with custom cells. Each of these cells, have inside a uicollectionview, with a horizontal scrolling.
I am working programmatically, so the tableviewcell is the delegate/datasource for collectionview.
My datasource structure, is an array of arrays.
My tableview, has, for every tableviewcell, a tableview section.Tableview datasource methods work without problem using the array. I am able to set up the tableview correctly.
Inside this cell, i want to display a collectionview, with horizontal scrolling.
The problem which i am encountering is i cannot assign datasource correctly using the arrays to collectionview. What happens is when i load the tableview, and scrolling down, i see duplicate records, so for example the first 3 rows are displayed correctly(in terms of data and number of items),but from the 4th row, for example, data is duplicated, so i see again the records for the first 3 rows, and of course this does not have to happen, because if i scroll on the 4th line(the collectionview on the 4th row) the app crashes due to an index problem out of range.
This is simple to understand: lets say i have 10 cells on the first row, and 5 on the 4th row/or section, as you prefer... Scrolling the 4th row'scollection view will cause the crash. This is because of the wrong data which is actually the same from the first row: instead, i have only 5 cells to render...
Tecnique i am using is pretty simple: give each tableviewcell's tag the actual indexpath.section. Then in the collectionview, use this tag to loop through array and then the indexpath.item to get the correct array.
Lets get a look into the code now:
Tableview
func numberOfSections(in tableView: UITableView) -> Int {
return DataManager.shared.datasource.count
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as! DiarioTableViewCell
cell.tag = indexPath.section
return cell
}
TableviewCell
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: .default, reuseIdentifier: "cell")
collectionView.register(DiarioCVCell.self, forCellWithReuseIdentifier: "cellCV")
collectionView.delegate = self
collectionView.dataSource = self
DataManager.shared.istanzaCV = self.collectionView
addSubview(tableCellBG)
addSubview(collectionView)
setConstraints()
}
CollectionView
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
let tvCell = collectionView.superview as! DiarioTableViewCell
return DataManager.shared.datasource[tvCell.tag].count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellCV", for: indexPath) as! DiarioCVCell
let celltag = (collectionView.superview as! DiarioTableViewCell).tag
cell.datasource = DataManager.shared.datasource[celltag][indexPath.item]
return cell
}
Notice i have read all the possibly related threads, even ashfurrow's article, and here on stack, but i was not able to find a solution.
Thanks for any help!
Try to reload your collection view when cell is showing. Cells are being reused to save memory so they are created only once - you are setting all data at init and it's staying there forever.
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as! DiarioTableViewCell
cell.tag = indexPath.section
cell.collectionView.reloadData()
cell.collectionView.collectionViewLayout.invalidateLayout() //just to be sure, maybe it's not necessary
return cell
}
I Have a UITableView which is controlled by NSFetchedResultsController. I want to add single cell to the first row and make this cell static. In other words, there will be a button which will open another View Controller.
Until now, I was ok with fetched results controller and table. Now I'm a bit confused. How should I do this?
Instead using a header might be ok too, but I don't want this header to be on top all the time. I want this cell to be just like WhatsApp iOS "Create new group" cell on chats panel.
Thank you!
var dataArray = ["A","B","C"]
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.dataArray.count+1
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
if indexPath.row == 0
{
let cell = tableView.dequeueReusableCell(withIdentifier: "CreateNewGroupCell") as! CreateNewGroupCell
return cell
}
else
{
// Get the data from Array
let data = self.dataArray[indexPath.row-1]
// Logic to show other cells
let cell = tableView.dequeueReusableCell(withIdentifier: "OtherCell") as! OtherCell
return cell
// ....
}
}
You will need to create tableview with number of rows fetched from NSFetchedResultsController +1. Also in cellForRowIndex method you will need to add a check like indexPath.row == 0 and in there you will make the changes.
Also you will have to add action for that button within that section. You can also set different custom tableview for first row.
It can be similar to following:
func tableView(_ tableView: UITableView, cellForRowAtIndexPath indexPath: IndexPath) -> UITableViewCell {
if(indexPath.row==0){
let cell = tableView.dequeueReusableCell(withIdentifier: "CellWithButton", for: indexPath) as! CellWithButton
}
else{
let cell = tableView.dequeueReusableCell(withIdentifier: "OtherCells", for: indexPath) as! OtherCells
//here add data for cells from your array
}
return cell
}
Is there an iOS / Swift 3.0 callback method that tells when a UITableViewController has finished loading (creating the cells of) a UITableView (after calling the .reloadData on the table view (in Swift)?
(or alternative method)
The func you're looking for doesn't exist, but per your comment above, would it be possible to get each cell (or some model object it takes as a property) to make the API pre-load call? In this way, data will only be pre-loaded for visible cells. When new cells are scrolled into view, their data will be loaded in turn.
For example, in your cell:
class MyCell: UITableViewCell {
var someObject: MyObject {
didSet {
someObject?.loadData()
}
}
}
and in your view controller:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath) as! "MyCell"
cell.someObject = myObjects[indexPath.row]
return cell
}
This way you're only loading data for cells in view. If you were to add:
func tableView(_ tableView: UITableView, didEndDisplaying cell: UITableViewCell, forRowAt indexPath: IndexPath) {
cell.someObject.cancelLoading()
}
You can ensure that objects in cells no longer view aren't loaded if not required.