Tableview crashes when reloading data - ios

Question

I've unexpected problems with tableviews. It seems that the app quits without a error every time I try to reload my tableviews' data. I know that the array is formed correctly, so there's something wrong with these functions:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if tableView.tag == 1 {
return latest.count
}
else if tableView.tag == 2{
return older.count
}
else {
return 0 //In case of error
}
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
var cell:UITableViewCell?
if tableView.tag == 1 {
print("Success")
cell = tableView.dequeueReusableCell(withIdentifier: "latestCell")! as UITableViewCell
cell = UITableViewCell(style: UITableViewCellStyle.subtitle,
reuseIdentifier: "latestCell")
cell?.textLabel?.text = latest[indexPath.row]
cell?.detailTextLabel?.text = latestSub[indexPath.row]
cell?.accessoryType = .disclosureIndicator
return cell!
}
else if tableView.tag == 2 {
cell = tableView.dequeueReusableCell(withIdentifier: "olderCell")! as UITableViewCell
cell = UITableViewCell(style: UITableViewCellStyle.subtitle,
reuseIdentifier: "olderCell")
cell?.textLabel?.text = older[indexPath.row]
cell?.detailTextLabel?.text = olderSub[indexPath.row]
cell?.accessoryType = .disclosureIndicator
return cell!
}
else {
return cell!
}
}
The answers before to these type of questions here were about forgetting to set delegates and datasource and so... So I believe this is an appropriate question.
Thanks in advance!
EDIT:
var latest = [String]()
var older = [String]()
var latestSub = [String]()
var olderSub = [String]()
override func viewDidAppear(_ animated: Bool) {
latestTable.reloadData()
olderTable.reloadData()
}
The full log;
2017-02-16 15:57:28.889 NotebookApp[24985:604704] Firebase automatic screen reporting is enabled. Call +[FIRAnalytics setScreenName:setScreenClass:] to set the screen name or override the default screen class name. To disable automatic screen reporting, set the flag FirebaseAutomaticScreenReportingEnabled to NO in the Info.plist
2017-02-16 15:57:28.997 NotebookApp[24985:] Firebase Analytics v.3600000 started
2017-02-16 15:57:28.999 NotebookApp[24985:] To enable debug logging set the following application argument: -FIRAnalyticsDebugEnabled
2017-02-16 15:57:29.012: FIRInstanceID AppDelegate proxy enabled, will swizzle app delegate remote notification handlers. To disable add "FirebaseAppDelegateProxyEnabled" to your Info.plist and set it to NO
2017-02-16 15:57:29.020 NotebookApp[24985:] Successfully created Firebase Analytics App Delegate Proxy automatically. To disable the proxy, set the flag FirebaseAppDelegateProxyEnabled to NO in the Info.plist
2017-02-16 15:57:29.090 NotebookApp[24985:] The AdSupport Framework is not currently linked. Some features will not function properly.
2017-02-16 15:57:29.180 NotebookApp[24985:] Firebase Analytics enabled
2017-02-16 15:57:45.703779 NotebookApp[24985:604704] [LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"",
""
)
Will attempt to recover by breaking constraint
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in may also be helpful.
2017-02-16 16:01:34.316879 NotebookApp[24985:604704] [MC] System group container for systemgroup.com.apple.configurationprofiles path is /Users/tuomasnummela/Library/Developer/CoreSimulator/Devices/AA87179A-11E5-4A3A-A63F-B785AA71EC95/data/Containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles
2017-02-16 16:01:34.317476 NotebookApp[24985:604704] [MC] Reading from private effective user settings.
I kind of didn't think that there would be anything useful here because when the app quits it doesn't take me to the error-page-thing and highlight any code.
What my project looks like after the app has forcedly closed itself.

Answer 1

The things that can go wrong here is it can't find the cell with the reuse identifier that you are passing in the below line
cell = tableView.dequeueReusableCell(withIdentifier: "olderCell")! as UITableViewCell
All you have to do is register the cell with reuse identifier in your viewDidLoad
<olderTableView>.registerClass(UITableViewCell.self, forCellReuseIdentifier: "olderCell")
<latestTableView>.registerClass(UITableViewCell.self, forCellReuseIdentifier: "latestCell")
or
you can simply replace the dequeue and initialization lines with the following
if tableView.tag == 1 {
let reuseId = "latestCell"
let latestCell = tableView.dequeueReusableCell(withIdentifier: reuseId) ?? UITableViewCell(style: .subtitle, reuseIdentifier: reuseId)
latestCell.textLabel?.text = latest[indexPath.row]
latestCell.detailTextLabel?.text = latestSub[indexPath.row]
latestCell.accessoryType = .disclosureIndicator
return latestCell
}

Answer 2

The first error is in the viewDidAppear you must call the super.viewDidAppear(animated), the tableview reload will never fired.

Answer 3

You have a number of errors in func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell. The crash is likely from force unwrapping cell which was nil in the last line.
Here is my stab at cleaning it up. Be sure to register you UITableViewCell subclass with tableView.register(SubtitleCell.self, forCellReuseIdentifier:"latestCell"). Unless there is other code not visible, you can use the same identifier for latestCell and olderCell - they don't seem to be different from the code you've posted
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
var cell:UITableViewCell //can't be optional
if tableView.tag == 1 {
print("Success")
cell = tableView.dequeueReusableCell(withIdentifier: "latestCell", forIndexPath: indexPath) as! SubtitleCell
//cell = UITableViewCell(style: UITableViewCellStyle.subtitle, reuseIdentifier: "latestCell") //don't call this here, make a subclass of UITableViewCell to set style
cell.textLabel?.text = latest[indexPath.row]
cell.detailTextLabel?.text = latestSub[indexPath.row]
cell.accessoryType = .disclosureIndicator
return cell
}
else if tableView.tag == 2 {
//same comments as above
cell = tableView.dequeueReusableCell(withIdentifier: "olderCell", for: indexPath) as! SubtitleCell
cell.textLabel?.text = older[indexPath.row]
cell.detailTextLabel?.text = olderSub[indexPath.row]
cell.accessoryType = .disclosureIndicator
return cell
}
else {
cell = tableView.dequeueReusableCell(withIdentifier: "latestCell", forIndexPath: indexPath)
return cell //you were returning nil here - need to return a cell
}
}
Here is an example of how to init the correct cell style
class SubtitleCell: UITableViewCell {
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: .subtitle, reuseIdentifier: reuseIdentifier)
}