Getting Crash in cellForRowAtIndexPath in tableView on Crashlytics - ios

Question

I got weird crash on Crashlytics, It's showing crash in the line as commented in code.
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
if indexPath.row >= collectionArrayApiObject.collectionsArray.count {
return UITableViewCell(frame: CGRectZero)
}
var tableViewCell:CollectionsTableViewCell? = tableView.dequeueReusableCellWithIdentifier("collectionsCell") as? CollectionsTableViewCell
if (tableViewCell == nil) {
tableViewCell = CollectionsTableViewCell(style: .Default, reuseIdentifier: "collectionsCell")
}
// Got crash in below line
let collectionObject = collectionArrayApiObject.collectionsArray[indexPath.row]
tableViewCell!.setCollection(collectionObject)
return tableViewCell!
}
This is the stack trace that I got..
But not getting why this even happened? I have already put check that
index.row >= collectionArrayApiObject.collectionsArray.count
so it should not be index out of range case. Can any one give me just one case in which this can happen?
NOTE: This happened with only one user till now but still why this even happened?
Whole Table View Controller:
import UIKit
class CollectionsViewController: CUIBaseViewController, CollectionArrayApiObjectDelegate, UITableViewDataSource, UITableViewDelegate, UIViewControllerPreviewingDelegate {
var collectionsTableView : UITableView?
var collectionArrayApiObject : CollectionArrayApiObject = CollectionArrayApiObject()
var headerSearchButton : UIBarButtonItem?
var cityId: String?
required init?(coder aDecoder: NSCoder) {
fatalError("NSCoding not supported")
}
override init(nibName nibNameOrNil: String!, bundle nibBundleOrNil: NSBundle!) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}
convenience init(CityId: String? = nil) {
self.init(nibName: nil, bundle: nil)
self.cityId = CityId
self.view.backgroundColor = Colors.white()
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.setUpHeaderView()
self.createTableView()
self.getData()
self.listenToNotifications()
self.automaticallyAdjustsScrollViewInsets = false
if #available(iOS 9.0, *) {
registerForPreviewingWithDelegate(self, sourceView: collectionsTableView!)
}
}
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
self.navigationController?.setNavigationBarHidden(false, animated: animated)
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
}
func listenToNotifications() {
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(CollectionsViewController.cityChanged), name: Constants.NOTIFIICATION_LOCATION_CHANGED_CITY, object: nil)
}
func cityChanged() {
self.getData()
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
collectionsTableView?.frame = CGRectMake(0, Constants.NAV_BAR_HEIGHT, self.view.width, self.view.height - Constants.NAV_BAR_HEIGHT)
}
//MARK: view creation functions
func setUpHeaderView() {
self.navigationItem.title = "Collections"
let negativeSpacer = UIBarButtonItem.init(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
negativeSpacer.width = 0;
headerSearchButton = UIBarButtonItem.init(title: "n", style: .Plain, target: self, action: #selector(CollectionsViewController.headerSearchButtonTapped))
headerSearchButton?.width = 40
headerSearchButton?.setTitleTextAttributes([NSFontAttributeName: Fonts.iconFont(18), NSForegroundColorAttributeName: Colors.gray()], forState: .Normal)
self.navigationItem.rightBarButtonItems = [negativeSpacer, headerSearchButton!];
}
func createTableView() {
collectionsTableView = UITableView(frame: CGRectZero, style: .Plain)
collectionsTableView?.separatorStyle = .None
collectionsTableView?.backgroundColor = Colors.white()
collectionsTableView?.dataSource = self
collectionsTableView?.delegate = self
self.view.addSubview(collectionsTableView!)
}
//MARK : tableview delegate methods
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1;
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return collectionArrayApiObject.collectionsArray.count
}
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return CollectionsTableViewCell.getHeight()
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
if indexPath.row >= collectionArrayApiObject.collectionsArray.count {
return UITableViewCell(frame: CGRectZero)
}
var tableViewCell:CollectionsTableViewCell? = tableView.dequeueReusableCellWithIdentifier("collectionsCell") as? CollectionsTableViewCell
if (tableViewCell == nil) {
tableViewCell = CollectionsTableViewCell(style: .Default, reuseIdentifier: "collectionsCell")
}
let collectionObject = collectionArrayApiObject.collectionsArray[indexPath.row]
tableViewCell!.setCollection(collectionObject)
return tableViewCell!
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
Commons.trackEvent(Commons.createGAcategory([Constants.COLLECTIONS_PAGE, "collection"]), action: "click", label: nil, value: 1)
let exploreFeedForCollection = ExploreFeedViewController.init(collection: collectionArrayApiObject.collectionsArray[indexPath.row])
//self.presentViewController(CUINavigationController.init(rootViewController: exploreFeedForCollection), animated: true, completion: nil)
self.navigationController?.pushViewController(exploreFeedForCollection, animated: true)
}
func scrollViewDidScroll(scrollView: UIScrollView) {
let contentOffset = scrollView.contentOffset.y
if (collectionsTableView != nil) {
for cell in collectionsTableView!.visibleCells {
if (cell.isKindOfClass(CollectionsTableViewCell.self)) {
let cellOffset = cell.y - contentOffset;
//image parallax
let parallaxCut: CGFloat = 0.5
let percent = (cellOffset + cell.height)/(collectionsTableView!.height + cell.height);
let extraHeight = cell.height * (CollectionsTableViewCell.parallaxRatio-1.0) * parallaxCut;
let collectionCell = cell as! CollectionsTableViewCell;
collectionCell.bgImageView.y = -extraHeight*percent;
}
}
}
}
//MARK : get cities data functions
func getData() {
collectionArrayApiObject = CollectionArrayApiObject()
collectionArrayApiObject.fetchCollections(Delegate: self, CityId: self.cityId)
if collectionArrayApiObject.collectionsArray.count == 0 {
self.showLoader("Hmm, things are getting interesting")
}
}
func collectionsFetchedSuccessfully() {
self.hideNothingHereViewAndLoader()
self.collectionsTableView?.reloadData()
self.scrollViewDidScroll(self.collectionsTableView!)
}
func collectionsFetchingFailed(errorType: ErrorType) {
self.showNothingHereView(errorType, icon: nil, showTryAgain: true)
}
override func didTapReloadButton() {
self.getData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//MARK: UIViewControllerPreviewingDelegate
func previewingContext(previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController? {
guard let indexPath = collectionsTableView?.indexPathForRowAtPoint(location) else{
return nil
}
// Lifting cell up on 3D touch before peeking
if #available(iOS 9.0, *) {
let cellRect = collectionsTableView?.rectForRowAtIndexPath(indexPath)
let sourceRect = previewingContext.sourceView.convertRect(cellRect!, fromView: collectionsTableView)
previewingContext.sourceRect = sourceRect
}
return ExploreFeedViewController.init(collection: collectionArrayApiObject.collectionsArray[(indexPath as NSIndexPath).row])
}
func previewingContext(previewingContext: UIViewControllerPreviewing, commitViewController viewControllerToCommit: UIViewController) {
self.navigationController?.pushViewController(viewControllerToCommit, animated: true)
}
//MARK : header button functions
func headerSearchButtonTapped() {
let searchVC = SearchViewController(CityId: cityId)
self.navigationController?.pushViewController(searchVC, animated: true)
}
deinit {
NSNotificationCenter.defaultCenter().removeObserver(self)
}
}

Answer 1

Some observations:
First
Instead of using this if statement:
if indexPath.row >= collectionArrayApiObject.collectionsArray.count {
return UITableViewCell(frame: CGRectZero)
}
You should use the numberOfRowsInSection to do that, like this:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return collectionArrayApiObject.collectionsArray.count
}
Second
In your cellForRowAtindexPath you just have to dequeue the cell and than set it as you need, like this:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
//swift 3.0
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! CollectionsTableViewCell
//swift 2.2
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! CollectionsTableViewCell
let collectionObject = collectionArrayApiObject.collectionsArray[indexPath.row]
cell.setCollection(collectionObject)
return cell
}
There isn't need to test if you use dequeueReusableCellWithIdentifier:forIndexPath:) which according to the docs always returns a valid cell

Answer 2

1- if you are using like this
let cell = tableChatHome.dequeueReusableCell(withIdentifier: "tableChatHomeCell1", for: indexPath) as! tableChatHomeCell1
2- change to like this work fine for me
let cell = tableView.dequeueReusableCell(withIdentifier: "tableChatHomeCell1") as! tableChatHomeCell1