I am having trouble understanding the UIKit crash reports that I am receiving:
Is there a way of finding out what line of code caused this:
Crashed: com.apple.main-thread
0 UIKit 0x195694264 __56-[UIPresentationController runTransitionForCurrentState]_block_invoke + 444
1 UIKit 0x1955d0950 _runAfterCACommitDeferredBlocks + 292
2 UIKit 0x1955c29ec _cleanUpAfterCAFlushAndRunDeferredBlocks + 528
3 UIKit 0x195336648 _afterCACommitHandler + 132
4 CoreFoundation 0x18f1c09a8 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32
5 CoreFoundation 0x18f1be630 __CFRunLoopDoObservers + 372
6 CoreFoundation 0x18f1bea7c __CFRunLoopRun + 956
7 CoreFoundation 0x18f0eeda4 CFRunLoopRunSpecific + 424
8 GraphicsServices 0x190b58074 GSEventRunModal + 100
9 UIKit 0x1953a9058 UIApplicationMain + 208
10 FlexConnect 0x1001b48c8 main (AppDelegate.swift:20)
11 libdyld.dylib 0x18e0fd59c start + 4
The error itself is:
Crashed: com.apple.main-thread
EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000010
EDIT:
Based of the answer below, I'm wondering if it is advisable to use:
func topMostController() -> UIViewController {
var topController: UIViewController = UIApplication.sharedApplication().keyWindow!.rootViewController!
while (topController.presentedViewController != nil) {
topController = topController.presentedViewController!
}
return topController
}
and always call
let topVC = topMostController().dismiss(animated: true, completion: nil)
everywhere in my app where I currently have self.dismiss(animated: true, completion: nil)?
Is this a necessary check or how can I pin down where self.dismiss is having an issue?
Some sample dismissals:
@IBAction func returnToDash(_ sender: UIButton) {
self.dismiss(animated: true, completion: nil)
}
let pending = UIAlertController(title: "\n\n\n\(title)", message: nil, preferredStyle: .alert)
displayActivityAlertWithCompletion2(ViewController: self, pending: pending){_ in
Helper_StatusCheck.doSync(_cleanSync: false){
Prefs.is_Syncing = false
DispatchQueue.main.async {
pending.dismiss(animated: true){
Toast(text: "Upload sync completed").show()
self.dismiss(animated: true, completion: nil)
}
}
}
}
where displayActivityAlertWithCompletion2 looks like:
public func displayActivityAlertWithCompletion2(ViewController: UIViewController, pending: UIAlertController, completionHandler: @escaping ()->())
{
//let pending = UIAlertController(title: "\n\n\n"+title, message: nil, preferredStyle: .alert)
//create an activity indicator
let indicator = UIActivityIndicatorView(frame: pending.view.bounds)
indicator.autoresizingMask = [.flexibleWidth, .flexibleHeight]
indicator.color = UIColor(rgba: Palette.loadingColour)
//add the activity indicator as a subview of the alert controller's view
pending.view.addSubview(indicator)
indicator.isUserInteractionEnabled = false
// required otherwise if there buttons in the UIAlertController you will not be able to press them
indicator.startAnimating()
ViewController.present(pending, animated: true, completion: completionHandler)
}
EDIT 2 :
Some sample popover methods in my app:
@IBAction func search(_ sender: UIButton) {
if let popView = UIStoryboard(name: "AssetCommon", bundle: nil).instantiateViewController(withIdentifier: "searchPop") as? searchPopVC {
popView.delegate = self
popView.modalPresentationStyle = .popover;
popView.popoverPresentationController?.delegate = self
popView.popoverPresentationController?.barButtonItem = searchButton
popView.popoverPresentationController?.permittedArrowDirections = .any
popView.preferredContentSize = CGSize(width: 300, height: 70)
self.present(popView, animated: true, completion: nil)
}
}
and search pop:
class searchPopVC: UIViewController
{
@IBOutlet weak var searchBar: UISearchBar!
weak var delegate: SearchPopDelegate?
override func viewDidLoad()
{
super.viewDidLoad()
searchBar.delegate = self;
}
override func didReceiveMemoryWarning()
{
super.didReceiveMemoryWarning()
}
@IBAction func performSearch(_ sender: UIButton)
{
let term = searchBar.text ?? "";
delegate?.performSearch(with: term)
self.dismiss(animated: true, completion: nil);
}
}
extension searchPopVC: UISearchBarDelegate
{
func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
let term = searchBar.text ?? "";
delegate?.performSearch(with: term);
self.dismiss(animated: true, completion: nil)
}
}
You won't be able to find the line of code from this crash. However, this crash happens when the view controller you use to call dismiss(animated:completion:)
is removed from the view hierarchy prior to the animation completing.
Depending on how your code is setup, you can try to request a view controller higher up to call the dismissal. Another solution could be to retain the view controller in a property until your for sure done with it.
Edit: 1/5/18
In response to the comments, here is an example of how a function can be made for view controllers that logs an event and dismisses.
extension UIViewController {
func dismissAndLog(animated: Bool, completion: (() -> ())? = nil) {
// Here are two examples of how your view controller can be identified.
// let id = title
let id = String(describing: type(of: self))
CLSLogv("Dismissed View Controller: %@", getVaList([id]))
dismiss(animated: animated, completion: completion)
}
}
I'm not entirely familiar with Crashlytics or their API, so if this logging is giving you issues, you can check out these links.
Also I don't know how they provide the data to you, so I can't explain to you the best way to parse it. However certainly the timestamps can be successfully used as a final solution. You can also try emailing their support asking for the best way to map these logs to the crash.