Swift 3 - Problems in reusing cell with multiple custom cells - ios

Question

I've got problems when I scroll down in my UITableview. The table shows me cells with old content when the cell is reused.
The Probleme is the following:
Swift wants to reuse an old cell, but doesn't properly clear the old content from the old cell. This leads to cells with old content, although I'm providing new data to the cells.
Architecture of the UITableView if the following:
Each custom cell has their own identifier
Each custom cell is separated in an own class
Screenshots of the problem:
Beginning of the Questionnaire Screen Shot:
The scrolled down table:
The problem here is the "Handedness"-Cell which is showing the cell number 3 (because of the reuse of the cell), which is not right
The numberOfSection-Method
override func numberOfSections(in tableView: UITableView) -> Int {
return 2
}
The numberOfRowsInSection-Method
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if(section == 0){
return questionnaireStructure.count
} else {
return 1
}
}
The cellForRowAt-Method
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
// first section is the normal Questionnaire
if(indexPath.section == 0){
// current questionnaireStructure
let questStruct:QuestionnaireStructure? = questionnaireStructure[indexPath.row]
// current cell is a "Headline"
if(questStruct?.elementtype == "elements/headlines"){
let cell = tableView.dequeueReusableCell(withIdentifier: "HeadlineStructureCellID", for: indexPath) as! Headline
cell.headline.text = questStruct?.headline
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
} else if(questStruct?.elementtype == "elements/texts"){
// current cell is a "texts"
let cell = tableView.dequeueReusableCell(withIdentifier: "TextsStructureCellID", for: indexPath) as! Texts
cell.textsLabel.text = questStruct?.text
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
} else if(questStruct?.questiontype == "Slider"){
// currrent cell is a "slider-Question"
let cell = tableView.dequeueReusableCell(withIdentifier: "QuestionSliderStructureCellID", for: indexPath) as! Slider
cell.sliderQuestion.text = questStruct?.question
cell.selectionStyle = UITableViewCellSelectionStyle.none
let values = (questStruct?.values)!
let valueArray = values.array as! [Values]
cell.slider.minimumValue = Float(valueArray[0].min)
cell.slider.maximumValue = Float(valueArray[0].max)
let answers = (questStruct?.answers)!
let answerArray = answers.array as! [Answers]
cell.minLabel.text = answerArray[0].label
cell.maxLabel.text = answerArray[1].label
return cell
} else if(questStruct?.questiontype == "SingleChoice"){
let cell = tableView.dequeueReusableCell(withIdentifier: "QuestionSingleChoiceStructureCellID", for: indexPath) as! SingleChoiceCell
let radioButtonController = SSRadioButtonsController()
radioButtonController.delegate = self
radioButtonController.shouldLetDeSelect = true
cell.radioButtonController = radioButtonController
cell.updateCellData(questStruct: questStruct!, indexInTable: indexPath.row)
return cell
} else if(questStruct?.questiontype == "MultipleChoice"){
let cell = tableView.dequeueReusableCell(withIdentifier: "QuestionMultipleChoiceStructureCellID", for: indexPath) as! MultipleChoiceCell
cell.multQuestionLabel.text = questStruct?.question
cell.questStruct = questStruct
return cell
} else if(questStruct?.questiontype == "YesNoSwitch"){
let cell = tableView.dequeueReusableCell(withIdentifier: "QuestionYesNoSwitchStructureCellID", for: indexPath) as! YesNoSwitch
cell.yesNoQuestion.text = questStruct?.question
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
} else if(questStruct?.questiontype == "TextDate"){
let cell = tableView.dequeueReusableCell(withIdentifier: "Datepicker", for: indexPath) as! DatePicker
cell.question.text = questStruct?.question
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
} else {
let cell = tableView.dequeueReusableCell(withIdentifier: "QuestionSingleChoiceStructureCellID", for: indexPath) as! SingleChoiceCell
//cell.singleChoiceLabel.text = questStruct?.question
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
}
} else {
//last section is the save button
// show the save button when the Questionnaire is loaded
if(questionnaireStructure.count != 0){
let cell = tableView.dequeueReusableCell(withIdentifier: "SaveStructureCellID", for: indexPath) as! SaveQuestionnaire
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
} else {
let cell = tableView.dequeueReusableCell(withIdentifier: "TextsStructureCellID", for: indexPath) as! Texts
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
}
}
}
What I checked:
the data of "questStruct" is providing the latest data
overriding the "prepareForReuse"-Methode without success

Answer 1

Here:
} else {
let cell = tableView.dequeueReusableCell(withIdentifier: "QuestionSingleChoiceStructureCellID", for: indexPath) as! SingleChoiceCell
//cell.singleChoiceLabel.text = questStruct?.question
cell.selectionStyle = UITableViewCellSelectionStyle.none
return cell
}
You need to "reset" the cell in case it's being reused. Options are:
write a reset() function in the cell, to clear any assigned data and display "default" content, or
create an empty questStruct and call cell.updateCellData(questStruct: questStruct!, indexInTable: indexPath.row)
Option 1. is probably the easiest and most straight-forward.

Answer 2

Are you sure the data isn't actually duplicated in the questStruct array? If that's not the case then all I can think is that it looks like you have two places where a single choice cell is used. In one of them you set a bunch of data, while in the other one you don't seem to set any data. I'm talking about that last else statement where you have the part where you set singleChoiceLabel.text except it's commented out. If that condition gets hit and it's reusing a cell that was configured for the other singleChoiceStructure branch of the if condition then the information will still be filled out from the previous configuration. It's possible the questionType property of one of your QuestionnaireStructure objects is either spelled incorrectly or just a value you haven't accounted for, which is causing the if statement to hit the else which returns an unconfigured QuestionSingleChoice cell that might still have information from the last time it was used.