passing data from UItableviewController to UItableViewcell

Question

I cannot understand why some values are well passed from the tableViewController to my custom UITableViewCell, and some others are not.

In my UItableviewController.cellForRowAtIndexPath i set up a cell with some values, before returning this cell :

cell.label1.text = myCustomObject.id
cell.label2.text = myCustomObject.path
cell.myCustomObjectCellMember = myCustomObject
cell.pathCellMember = myCustomObject.path

return cell

On the custom UITableViewCell side, in awakeFromNib method, the two first cell members are Ok, the two last ones contain nil.

The only difference between the two first cell members and the two last ones is that the two first are declared as IBOutlet and linked to the storyboard, while the two others are not linked to the UI. But yet, it should be OK to write in these vars from the tableViewController, right ?

Here are the declarations of these variables in the custom UITableViewCell:

@IBOutlet weak var label1: UILabel!    
@IBOutlet weak var label2: UILabel!    
var pathCellMember : String!
var myCustomObjectCellMember: MyCustomObjectCellMember!

When logged (inside UITableViewCell.awakeFromNib), label1.text and label2.text show the correct value, but pathCellMember and myCustomObjectCellMember display nil instead of the value assigned in UItableviewController.cellForRowAtIndexPath.

As requested, a more explicit code :

  class CustomCellTableViewCell: UITableViewCell {       

       @IBOutlet weak var label1: UILabel!    
       @IBOutlet weak var label2: UILabel!    
       var pathCellMember : String!
       var myCustomObjectCellMember: MyCustomObjectCellMember!

        override func awakeFromNib() {
            super.awakeFromNib()

            println("label1 : \(self.label1.text!)") //displays the value assigned
            println("label2 : \(self.label2.text!)") //displays the value assigned
            println("pathCellMember: \(self.pathCellMember!)") //displays nil
            println("myCustomObjectCellMember.path : \(self.myCustomObjectCellMember.path)") //displays `nil`
        }

Thank you

Can you post your awakeFromNib code and specify where exactly it is being called? — Aloha Silver
– Aloha Silver, Commented Apr 21, 2015 at 16:37
I don't see how it's possible that you see the assigned values in awakeFromNib. When I put a log in cellForRowAtIndexPath right after the line where the cell is created, that log prints out after the logs in the cell. awakeFromNib is just too early to check these values. My logs in the cell show the values that were set in IB, not the ones assigned in cellForRowAtIndexPath. — rdelmar
– rdelmar, Commented Apr 21, 2015 at 16:55
@rdelmar has a good point. You should try checking for the cell values in cellForRowAtIndexPath, not inside awakeFromNib. — Aloha Silver
– Aloha Silver, Commented Apr 21, 2015 at 17:00
@TarikZouine: you could either try moving these assignments to tableView(_:willDisplayCell:forRowAtIndexPath:) instead of tableView(_:cellForRowAtIndexPath:) or going back to using UITapGestureRecognizers and asking another question (that should be easily solvable). — Aloha Silver
– Aloha Silver, Commented Apr 21, 2015 at 17:55

Mark McCorkle · Accepted Answer · 2015-04-21 17:04:29Z

2

In cellForRowAtIndexPath is where you will reuse (deque) each cell. This is where you need to assign your vars values to each cell. While awake does set the initial values they will only fire the first time before the cell is reused. Assign everything in cellForRow or willDisplayCell (background colors, etc).

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableView_Class/

Discussion For performance reasons, a table view’s data source should generally reuse UITableViewCell objects when it assigns cells to rows in its tableView:cellForRowAtIndexPath: method. A table view maintains a queue or list of UITableViewCell objects that the data source has marked for reuse. Call this method from your data source object when asked to provide a new cell for the table view. This method dequeues an existing cell if one is available or creates a new one using the class or nib file you previously registered. If no cell is available for reuse and you did not register a class or nib file, this method returns nil. If you registered a class for the specified identifier and a new cell must be created, this method initializes the cell by calling its initWithStyle:reuseIdentifier: method. For nib-based cells, this method loads the cell object from the provided nib file. If an existing cell was available for reuse, this method calls the cell’s prepareForReuse method instead.

answered Apr 21, 2015 at 17:04

Mark McCorkle

9,4322 gold badges34 silver badges42 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Tarik Zouine Over a year ago

In cellForRowAtIndexPath, i do use dequeueReusableCellWithIdentifier forIndexPath. And to this cell newly created, i assign some values, inside the cellForRowAtIndexPath method. But after that, the only vars i can read in awakeFromNib are the IBOutlets ones and not the two other vars

Mark McCorkle Over a year ago

Wait, why are you using awakeFromNib after that though? Everything needs to be done in cellForRow for any new cells. You can access your other variables from in there when you create a reference to your custom cell class. Post your cellForRowAtIndexPath function. I have a feeling your using UITableViewCell for the class instead of the custom CustomCellTableViewCell class.

Shourob Datta Over a year ago

I am facing same problem . and what the solution of this problem . how can i transfer data from into custom UITableviewCell class ? @Mark McCorkle

Collectives™ on Stack Overflow

passing data from UItableviewController to UItableViewcell

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related