I'm new to coding so I not sure how to fix this error:
private let cellReuseIdentifier = "ArticleViewCell"
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCellWithIdentifier(cellReuseIdentifier) as? UITableViewCell
if cell == nil {
cell = ArticleViewCell(style: UITableViewCellStyle.Default, reuseIdentifier: cellReuseIdentifier)
}
I get this error:
Downcast from 'UITableViewCell?' to 'UITableView only warps optionals; did you mean to use "!"?
I tried changing the ? to ! put it get an error also.
Try
let cell = tableView.dequeueReusableCellWithIdentifier("Cell",forIndexPath: indexPath) as! UITableViewCell
Also do not forget to return the cell.
return cell
You do not need to unwrap it at all:
var cell = tableView.dequeueReusableCellWithIdentifier(cellReuseIdentifier)
Try:
let cell = tableView.dequeueReusableCellWithIdentifier(cellReuseIdentifier) as! <ClassName>
Where "ClassName" is the name of the class for the article tableview cell.
after you create cell, when you use it you should add a "!" after the cell such as:
return cell!
Related
I have two tableviews with two different custom tableview cells.. and am doing this:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if tableView == self.tableview {
let cell = tableview.dequeueReusableCell(withIdentifier: "matchescell") as! MatchesTableViewCell
// ......
return cell
} else {
let cell = tableview.dequeueReusableCell(withIdentifier: "filtercell") as! FilterTableViewCell
// ......
return cell
}
}
and of course i have registered them both from storyboard...
but i keep getting this:
on this line:
let cell = tableview.dequeueReusableCell(withIdentifier: "filtercell") as! FilterTableViewCell
tried to register them like this:
tableview.register(MatchesTableViewCell.self, forCellReuseIdentifier: "matchescell")
filterdrop.register(FilterTableViewCell.self, forCellReuseIdentifier: "filtercell")
but still getting the same error!
What am doing wrong?!
The problem is that you typed "tableview" instead of "tableView" in your else part:
replace :
let cell = tableview.dequeueReusableCell(withIdentifier: "filtercell") as! FilterTableViewCell
with :
let cell = tableView.dequeueReusableCell(withIdentifier: "filtercell") as! FilterTableViewCell
It is crashing because your "tableview" doesn't have this cell registered.
Add the "filtercell" identifier in the storyboard or xib custom cell (FilterTableViewCell).
Possible cause:
You haven't registered the class or the nib of the cell to the proper tableview
You haven't set the identifier in the cellview in you nib/storyboard
You have inverted the tableview and their cell type
This because you either didn't register the cell
tableView.register(CustomCellClass.self, forCellReuseIdentifier: "CellID")
//
tableView.register(UINib(nibName: "CustomCellClass", bundle: nil), forCellReuseIdentifier: "CellID")
or you swapped the dequeuing line for the tables
Have a look into your Tableview controller in the Storyboard. You should have another indentier than called in:
let cell = tableview.dequeueReusableCell(withIdentifier: "filtercell") as! FilterTableViewCell
BTW, you should always use this newer function
dequeueReusableCell(withIdentifier:for:)
instead of
dequeueReusableCell(withIdentifier:)
See this post for details.
You can easily solve this problem just to check what tableview you use at that time.
you can try this code,
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) {
if (tableview == (yourtableview 1)) {
let cell = yourtableview 1.dequeueReusableCell(withIdentifier: "yourtableview Cell 1") as? yourtableview Cell 1
// write your code for tableview 1
return cell
}
else
{
let cell = yourtableview 2.dequeueReusableCell(withIdentifier: "yourtableview Cell 2") as? yourtableview Cell 2
// write your code for tableview 2
return cell
}
}
I am getting following errors:
1) Non-optional expression of type 'UITableViewCell' used in a check for optionals
2) Value of type 'UITableViewCell' has no member 'congigureCell'
Please
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if let cell:UITableViewCell = countryList.dequeueReusableCell(withIdentifier: "cell")! as UITableViewCell // Error 1 happens here {
let text: String!
if inSearchMode {
text = filteredCountriesList[indexPath.row]
} else {
text = countriesList[indexPath.row]
}
cell.congigureCell(text: text) // Error 2 happens here
return cell
} else {
return UITableViewCell()
}
}
1) The ! mark at the end of
countryList.dequeueReusableCell(withIdentifier: "cell")!
uses force unwrap to make it non-optional, so you shouldn't check it inside if let, or even better way is to just remove ! mark
2) congigureCell probably the method of different class, not UITableViewCell. You should substitude UITableViewCell by this class to cast it
Make sure you have done following steps.
Add cell identifier in storyboard to your custom cell. i.e "cell"
Assign delegate and datasource of your YourTableview to YOURViewController.swift via storyboard or in code.
In YOURViewController.swift access cell using datasource of table
view as.
Add a custom class of sub class UITableViewCell and assign it to
tour cell in storyboard.
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if let cell = countryList.dequeueReusableCell(withIdentifier: "cell") as! YOURTableViewCellClass {
let text: String!
if inSearchMode {
text = filteredCountriesList[indexPath.row]
} else {
text = countriesList[indexPath.row]
}
cell.congigureCell(text: text) // Error 2 happens here
return cell }
The ! mark is uses to force unwrap the optional value that can be nil. But "if let" and "guard let" has been check for optionals, so you don't need ! mark.
Just use
if let cell:UITableViewCell = countryList.dequeueReusableCell(withIdentifier: "cell") as UITableViewCell
cell in this line is 'UITableViewCell', but congigureCell is not a member of UITableViewCell.
If you want to use your own cell(like MyCell), you should convert it to MyCell.
let myCell = cell as! MyCell
1 .Instead of dequeueReusableCellWithIdentifier: use dequeueReusableCellWithIdentifier:forIndexPath: the later one never provides a nil value so you dont need to worry about the 'nil error'.
2.UItableViewCell dont have configure cell or congigureCell as in your case instead you have to create a custom tableViewCell and add function as configureCell() and then in this line
if let cell:UITableViewCell = countryList.dequeueReusableCell(withIdentifier: "cell")! as UITableViewCell
replace as UITableViewCell as as yourCustomTableViewCellClass
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("nameCell", forIndexPath: indexPath)
let pancakeHouse = pancakeHouses[indexPath.row]
if let cell = cell as? FAQsViewCell {
cell.pancakeHouse = pancakeHouse
} else {
cell.textLabel?.text = pancakeHouse.que
}
return cell
}
I got error in this function of UITableViewController when I run my project at that time I got it I can't understand why it came or what is its meaning.
The "definition conflicts with previous value" occurred also when you forgot to set the Cell Identifier
Make sure you have set the correct identifier to your custom cell (in your case "nameCell") :
I have currently have two UITableViews populated with contacts for the app. I have one for simply viewing them and editing/deleting and one for searching/picking contacts from a list. However, I'm getting a returned nil value when trying to use the same custom class cell for both UITableViews.
These are my two cellForRowAtIndexPath functions.
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = self.tableView.dequeueReusableCellWithIdentifier("SecondCell") as! ContactCell
let item = contacts[indexPath.row]
cell.meetupLabel?.text = item.fullName
return cell
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = self.tableView.dequeueReusableCellWithIdentifier("FirstCell") as! ContactCell
let item = contacts[indexPath.row]
cell.label?.text = item.fullName
return cell
}
If the table did not have a cell named FirstCell or SecondCell, the dequeueReusableCellWithIdentifier(_:) method will return nil, and you will need to construct the cell yourself.
// no don't do this.
let cell: ContactCell
if let c = tableView.dequeueReusableCell(withIdentifier: "FirstCell") as? ContactCell {
cell = c
} else {
cell = ContactCell(style: .default, reuseIdentifier: "FirstCell")
}
You should use dequeueReusableCell(withIdentifier:for:), which was introduced in iOS 6, if you would like UIKit to construct the cell for you:
// swift 3
let cell = tableView.dequeueReusableCell(withIdentifier: "FirstCell",
for: indexPath) as! ContactCell
// swift 2
let cell = tableView.dequeueReusableCellWithIdentifier("FirstCell",
forIndexPath: indexPath) as! ContactCell
...
Also, check if you have given the correct reuse-identifiers to the cells correctly in the interface builder.
As you said you are getting nil, my quick guess is that you haven't registered the cell at some point, runs earlier than this cell event. Look at this thread on how to register cell.
I have a tableview in my app and when I start my app it crashes on the following function.
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
// Configure the cell...
let cellId: NSString = "Cell"
var cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellId) as UITableViewCell
}
It crashes on the line of var cell
It gives the following error:
I can't figure out what's wrong with my code.
The whole function:
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
// Configure the cell...
let cellId: NSString = "Cell"
var cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellId) as UITableViewCell
let data: NSManagedObject = mylist[ip.row] as NSManagedObject
cell.textLabel.text = data.valueForKeyPath("voornaam") as String
cell.detailTextLabel.text = data.valueForKeyPath("achternaam") as String
return cell
}
EDIT:
What I got now:(Still gives the same error)
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell? {
// Configure the cell...
let cellId: NSString = "Cell"
var cell: UITableViewCell? = tableView?.dequeueReusableCellWithIdentifier(cellId) as? UITableViewCell
if cell == nil {
cell = UITableViewCell(style: .Subtitle, reuseIdentifier: cellId)
}
let data: NSManagedObject = mylist[indexPath.row] as NSManagedObject
cell!.textLabel.text = data.valueForKey("voornaam") as String
cell!.detailTextLabel.text = data.valueForKey("achternaam") as String
//cell!.textLabel.text = "Hoi"
return cell
}
This is happening because the as operator is defined to cast an object to a given type and crash if the conversion fails. In this case, the call to dequeue returns nil the first time you call it. You need to use the as? operator, which will attempt to cast the given object to a type, and return an optional that has a value only if the conversion succeeded:
var cell: UITableViewCell? = tableView.dequeueReusableCellWithIdentifier(cellId) as? UITableViewCell
if cell == nil {
cell = UITableViewCell(style: .Subtitle, reuseIdentifier: cellId)
}
...
Because cell is now an optional value, use cell! when you want to call methods on it to force-unwrap the UITableViewCell inside it.
Additionally, your code had a second problem: it never created a fresh cell. dequeue will return nil the first time it's called on your table view. You need to instantiate a new UITableViewCell as in my code sample and then return it from the cellFor... method. The table view will then save the cell and return it on future calls to dequeue.
First off, why are you doing an optional binding on line if let ip = indexPath? This argument is not optional and you don't need to do optional binding or unwrap it. But this shouldn't cause your code to crash.
Remove your let data line and assign literal strings to your cells and see if it still crashes.
May I suggest that you check to see if you set the tableview's delegates? I made that mistake once in the flurry of setting everything else up.
Perhaps it is too late but I like to share my experience. I had similar error as I copied the entire code from another project. So I think the variables and functions won't be recognised so I had to drag them (cntr+drag) then it is solved.
Sorry if I couldn't explain better. I am new this.