问题
Having trouble understanding a crash report in Crashlytics. I do not have much experience in analyzing crash report. Appreciate your help.
This is the crash log:
Crashed: com.apple.main-thread
0 My App 0x100f77180 specialized closure #1 in closure #1 in ConfirmItemCheckInViewController.doneButtonPressed() (ConfirmItemCheckInViewController.swift:175)
1 My App 0x100f77c94 partial apply for closure #1 in closure #1 in ConfirmItemCheckInViewController.doneButtonPressed() (ConfirmItemCheckInViewController.swift)
2 My App 0x100f95650 thunk for @callee_owned (@owned UIAlertAction) -> () (SettingsViewController.swift)
3 UIKit 0x18e4f5cf4 -[UIAlertController _invokeHandlersForAction:] + 108
4 UIKit 0x18e4f66ec __103-[UIAlertController _dismissAnimated:triggeringAction:triggeredByPopoverDimmingView:dismissCompletion:]_block_invoke.459 + 28
5 UIKit 0x18e33b030 -[UIPresentationController transitionDidFinish:] + 1320
6 UIKit 0x18e33ea20 __56-[UIPresentationController runTransitionForCurrentState]_block_invoke_2 + 188
7 UIKit 0x18e10a9d8 -[_UIViewControllerTransitionContext completeTransition:] + 116
8 UIKit 0x18e02fd7c -[UIViewAnimationBlockDelegate _didEndBlockAnimation:finished:context:] + 764
9 UIKit 0x18e02f70c -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 312
10 UIKit 0x18e02f418 -[UIViewAnimationState animationDidStop:finished:] + 296
11 UIKit 0x18e02f4b8 -[UIViewAnimationState animationDidStop:finished:] + 456
12 QuartzCore 0x188bd3d6c CA::Layer::run_animation_callbacks(void*) + 284
13 libdispatch.dylib 0x18456d048 _dispatch_client_callout + 16
14 libdispatch.dylib 0x184579b74 _dispatch_main_queue_callback_4CF$VARIANT$mp + 1016
15 CoreFoundation 0x184b8ff20 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
16 CoreFoundation 0x184b8dafc __CFRunLoopRun + 2012
17 CoreFoundation 0x184aae2d8 CFRunLoopRunSpecific + 436
18 GraphicsServices 0x18693ff84 GSEventRunModal + 100
19 UIKit 0x18e05b880 UIApplicationMain + 208
20 My App 0x100f4f924 main (AppDelegate.swift:15)
21 libdyld.dylib 0x1845d256c start + 4
Update: Added the code for doneButtonPressed. I do not make any changes to this part recently. This scene do not have any crash for 1.5 years since it is released.
func doneButtonPressed() {
if let signImage = signatureImage {
if let scheduleID = scheduleID {
if let driverID = driverID {
if let customerID = customerID {
let progressHUD = MBProgressHUD.showAdded(to: self.view, animated: true)
progressHUD.label.text = "Checking Item In"
NetworkLoader.sharedLoader.confirmCheckIn(signImage, shipmentID: scheduleID, customerID: customerID, driverID: driverID, items: items, valueAddedItems: self.valueAddedItemsList, completion: { (networkStatus, status) in
progressHUD.hide(animated: true)
if status {
// Remove saved signature
var index = SignatureData.sharedSignatureData.getSignatureIndex(scheduleID)
if index != -1 {
SignatureData.sharedSignatureData.sharedSignatureItems.remove(at: index)
}
// Remove saved item
index = PickupItemData.sharedPickupItemData.getPickupItemIndex(scheduleID)
if index != -1 {
PickupItemData.sharedPickupItemData.sharedPickupItems.remove(at: index)
}
let alert = UIAlertController(title: "Checked In", message: "", preferredStyle: UIAlertControllerStyle.alert)
let alertAction: UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: { (_) in
let myScheduleNC :UINavigationController = self.storyboard?.instantiateViewController(withIdentifier: "MyScheduleNavController") as! UINavigationController
self.revealViewController().pushFrontViewController(myScheduleNC, animated: true) // LINE 175 IS HERE
})
alert.addAction(alertAction)
self.present(alert, animated: true, completion: nil)
} else {
print(networkStatus.networkLoaderErrorDescription)
let alert = UIAlertController(title: networkStatus.networkLoaderErrorTitle, message: networkStatus.networkLoaderErrorDescription, preferredStyle: UIAlertControllerStyle.alert)
let alertAction: UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil)
alert.addAction(alertAction)
self.present(alert, animated: true, completion: nil)
}
})
}
}
}
}
}
回答1:
Adding [weak self] in the closure's completion block solves this.
You just stumbled upon a rare situation when self was released and was nil before the completion block was called, making the use of self. crash the application.
回答2:
It seems that somethings went wrong in your ConfirmItemCheckInViewController class. And more precisely, this error is in the doneButtonPressed() method at the line 175.
It would be helpful to have the corresponding code.
来源：https://stackoverflow.com/questions/47093409/understanding-crashlytics-crash-report-partial-apply