Swift two table view cell get the same value - swift

Question

I have used a tableview with 16 cells on a view controller. Each cell has a textfield and a picker view as a inputview for textfield. The odd thing is that When I choose the value for the first cell, it's fine. When I scrolled down to the last cell, the value is same as the first one. But I have never touched the last cell. Why would this happened?
func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
{
// selected value in Uipickerview in Swift
answerText.text = pickerDataSource[row]
answerText.tag = row
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
let cell = myTable.dequeueReusableCellWithIdentifier("addFollowCell", forIndexPath: indexPath) as! AddFollowTableViewCell
cell.questionView.text = listQuestion1[indexPath.row]
cell.pickerDataSource = dictPicker[indexPath.row]!
cell.answerText.addTarget(self, action: #selector(AddFollowUpViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingDidEnd)
return cell
}
func textFieldDidChange(sender: UITextField){
let rowIndex: Int!
let selectValue = sender.tag
if let txtf = sender as? UITextField {
if let superview = txtf.superview {
if let cell = superview.superview as? AddFollowTableViewCell {
rowIndex = myTable.indexPathForCell(cell)?.row
dictAnswer[rowIndex] = selectValue - 1
}
}
}
}
After two days, it solved by thousands of trials:
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
var cell = myTable.dequeueReusableCellWithIdentifier("addFollowCell") as! AddFollowTableViewCell
if(cell.identifier == true){
cell.answerText.text = selectedAnswerForRow[indexPath.row]
}
cell.questionView.text = listQuestion1[indexPath.row]
cell.pickerDataSource = dictPicker[indexPath.row]!
dictAnswer[indexPath.row] = cell.pickerValue
cell.answerText.addTarget(self, action: #selector(AddFollowUpViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingDidEnd)
cell.identifier = true
return cell
}
func textFieldDidChange(sender: UITextField){
let rowIndex: Int!
let cell = sender.superview?.superview as! AddFollowTableViewCell
rowIndex = myTable.indexPathForCell(cell)?.row
selectedAnswerForRow[rowIndex] = cell.answerValue
print(selectedAnswerForRow[rowIndex])
cell.answerText.text = sender.text
cell.identifier = true
}
It might have some performance issue need to be optimised , but it shows exactly what i want. LOL

Answer 1

You're basically recycling your views and not clearing them. That's the whole point of -dequeueReusableCellWithIdentifier:indexPath:.
Allocating and deallocating memory is very power consuming, so the system recycles every cell that goes out of viewport bounds.
You don't set the text inside answerText (I assume it's the text field that causes trouble) so its content will be kept when recycled.
Assuming you'll store user selection inside a dictionary var selectedAnswerForRow: [IndexPath:String]:
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
let cell = myTable.dequeueReusableCellWithIdentifier("addFollowCell", forIndexPath: indexPath) as! AddFollowTableViewCell
cell.questionView.text = listQuestion1[indexPath.row]
cell.pickerDataSource = dictPicker[indexPath.row]!
cell.answerText.addTarget(self, action: "textFieldDidChange:"), forControlEvents: UIControlEvents.EditingDidEnd)
cell.answerText.text = self.selectedAnswerForRow[indexPath] ?? "" // add this
return cell
}
self.selectedAnswerForRow[indexPath] ?? "" returns the result or an empty string if it's not present in the dictionary.
Also, you're adding several times the action for edition control event. You have to check first if it isn't already bound.

Answer 2

Because the cell is reused. So you have to implement prepareForReuse() in your custom cell class and reset all the changing variables
UPDATE
See :
class MyCell : UITableViewCell {
#IBOutlet weak var myTextField : UITextField!
//Add the following
override func prepareForReuse() {
myTextField.text = nil
myTextField.inputView = myPickerView
super.prepareForReuse()
}
}