Accessing cells that aren't visible on a UITableView - ios

Question

All my cells have a switch that moves the cell to the bottom of the table. It works fine, however when there is enough cells to drop below the visible bounds, I receive the error that the cell doesn't exist. This doesn't work because I need to update ALL cells sender.tag.
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell: TaskTableViewCell = tableView.dequeueReusableCellWithIdentifier("cell") as! TaskTableViewCell
var task = tasks[indexPath.row]
let index = tasks.indexOf(task)!
cell.cellSwitch.tag = index
cell.addSubview(cell.cellSwitch)
cell.tag = index
cell.cellSwitch.addTarget(self, action: "switched:", forControlEvents: UIControlEvents.TouchUpInside)
return cell
}
func switched(sender: UIButton) {
let indexPath = NSIndexPath(forRow: sender.tag, inSection: 0)
let finalIndexPath = NSIndexPath(forRow: tasks.count - 1, inSection: 0)
let task = tasks[indexPath.row]
tasks.removeAtIndex(indexPath.row)
tasks.append(task)
self.taskTableView.moveRowAtIndexPath(indexPath, toIndexPath: finalIndexPath)
for var i = 0; i < tasks.count; i ++ {
let cellIndex = NSIndexPath(forRow: i, inSection: 0)
let cell: TaskTableViewCell = self.taskTableView.cellForRowAtIndexPath(cellIndex) as! TaskTableViewCell
cell.cellSwitch.tag = cellIndex.row
}
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cellToBeReturned = UITableViewCell()
if indexPath.row != tableView.numberOfRowsInSection(0) - 1 {
let cell: TaskTableViewCell = tableView.dequeueReusableCellWithIdentifier("cell") as! TaskTableViewCell
var task = tasks[indexPath.row]
cell.cellFlatSwitch.removeFromSuperview()
cell.currentStreak.removeFromSuperview()
switch(task.icon) {
case "heart"?:
task.color = colors[0]
case "meditate"?:
task.color = colors[1]
case "leaf"?:
task.color = colors[2]
case "run"?:
task.color = colors[3]
case "muscle"?:
task.color = colors[4]
default:
task.color = .blackColor()
}
switch(task.icon) {
case "heart"?:
cell.pretickButton.setImage(Icons.imageOfHeartIcon, forState: .Normal)
case "meditate"?:
cell.pretickButton.setImage(Icons.imageOfMeditationIcon, forState: .Normal)
case "run"?:
cell.pretickButton.setImage(Icons.imageOfRunIcon, forState: .Normal)
case "leaf"?:
cell.pretickButton.setImage(Icons.imageOfLeafIcon, forState: .Normal)
case "muscle"?:
cell.pretickButton.setImage(Icons.imageOfMuscleIcon, forState: .Normal)
default:
cell.pretickButton.setImage(Icons.imageOfLeafIcon, forState: .Normal)
}
if task.longestStreak >= 21 {
cell.starImage.alpha = 1
} else {
cell.starImage.alpha = 0
}
if localSettings.habitPreview == "dayCounter" {
cell.currentStreak = LTMorphingLabel(frame: CGRectMake(11, 29, 39, 31))
cell.currentStreak.morphingEffect = LTMorphingEffect.Anvil
cell.currentStreak.textAlignment = NSTextAlignment.Center
cell.currentStreak.text = String(task.consecutiveDays!)
cell.addSubview(cell.currentStreak)
cell.streakSublabel.textAlignment = .Center
cell.currentStreak.adjustsFontSizeToFitWidth = true
cell.streakSublabel.adjustsFontSizeToFitWidth = true
cell.growthPreviewImage.hidden = true
cell.streakSublabel.hidden = false
} else {
if task.growth > 0 && task.growth <= 21 {
cell.growthPreviewImage.image = UIImage(named: "growth\(task.growth!)")
} else if task.growth <= 0 {
cell.growthPreviewImage.image = UIImage(named: "growth1")
} else if task.growth > 21 {
cell.growthPreviewImage.image = UIImage(named: "growht21")
}
cell.growthPreviewImage.hidden = false
cell.streakSublabel.hidden = true
}
if task.consecutiveDays == 1 {
cell.streakSublabel.text = "day"
} else {
cell.streakSublabel.text = "days"
}
cell.taskLabel.adjustsFontSizeToFitWidth = true
cell.taskLabel.text = task.name
cell.taskLabel.textColor = task.color
cell.cellFlatSwitch = AIFlatSwitch(frame: CGRectMake(300, 15, 70, 70))
cell.cellFlatSwitch.lineWidth = 2.3
cell.cellFlatSwitch.strokeColor = task.color!
cell.cellFlatSwitch.trailStrokeColor = task.color!
let index = tasks.indexOf(task)!
cell.pretickButton.tag = index
cell.backgroundColor = UIColor.clearColor()
cell.addSubview(cell.cellFlatSwitch)
cell.tag = index
cell.bringSubviewToFront(cell.pretickButton)
cell.pretickButton.addTarget(self, action: "switched:", forControlEvents: UIControlEvents.TouchUpInside)
cell.sendSubviewToBack(cell.cellFlatSwitch)
if task.doneToday == true {
cell.cellFlatSwitch.selected = true
cell.pretickButton.alpha = 0.0101
} else {
cell.cellFlatSwitch.setSelected(false, animated: false)
cell.pretickButton.alpha = 1.0
}
cellToBeReturned = cell
} else {
let cell: AddNewTableViewCell = tableView.dequeueReusableCellWithIdentifier("add") as! AddNewTableViewCell
cell.tag = indexPath.row
cellToBeReturned = cell
}
return cellToBeReturned
}
Any tips or help is greatly appreciated.

Answer 1

You are doing it wrong.
Don't call methods with NSIndexPath object references to move cells around. The implementation of UITableView suggests you should use one data source (could be an array, a dictionary, a custom NSObject, NSFetchedResultsController, etc) to implement all the relevant UITableViewDataSource and UITableViewDelegate delegate methods and you make updates to your data source first then call either reloadData or beginUpdates and endUpdates on your UITableView whenever you need to refresh your view.
In your case, I would simply use 2 NSMutableArray's, one for items with, one for without tags. Your switch handler should retrieve the item from the cell index path and move it from one array to the other. Then you can call beginUpdates and move your cell appropriately.
They key is to make changes to your data source first and in a way that is consistent to your UITableViewDataSource methods, especially the cellForAtIndexPath method. Basically the error you get is most likely because your data source is out of sync with the visible cells.
Hope this helps.