Re: iOS 8: Can any of you guys think of why an async creation of a UIAlert would generate an exception on a show?
Re: iOS 8: Can any of you guys think of why an async creation of a UIAlert would generate an exception on a show?
- Subject: Re: iOS 8: Can any of you guys think of why an async creation of a UIAlert would generate an exception on a show?
- From: Alex Zavatone <email@hidden>
- Date: Wed, 29 Jul 2015 15:54:23 -0400
Who's awesome?
Carl's awesome.
We had some other intermittent crashes around that area, related to a "use the first answer on SO approach", so I didn't think this would be that simple to isolate.
Oddly this is the only place where a UIAlertView crashes and our app is riddled with them since we have to support iOS 7 and 8.
The joy now is going through our app and making sure that we have a nice wrapper class to handle these UIAlertView/UIAlertController cases.
Thanks, man!
On Jul 29, 2015, at 3:01 PM, Carl Hoefs wrote:
> Could this issue be due to whatever reason Apple deprecated UIAlertView in iOS 8?
>
> "Important: UIAlertView is deprecated in iOS 8. (Note that UIAlertViewDelegate is also deprecated.) To create and manage alerts in iOS 8 and later, instead use UIAlertController with a preferredStyle of UIAlertControllerStyleAlert."
>
> -Carl
>
>> On Jul 29, 2015, at 11:40 AM, Alex Zavatone <email@hidden> wrote:
>>
>> Huh. Within the @try block, we can see that the navigationControllerSupportedInterfaceOrientations: is being sent to the UIAlertController.
>>
>> 2015-07-29 14:15:56.967[719:244869] -[SignInViewController displayErrorMessage:] [Line 289] <- ***
>> 2015-07-29 14:15:56.985 [719:244869] -[UIAlertController navigationControllerSupportedInterfaceOrientations:]: unrecognized selector sent to instance 0x156e29f0
>>
>> 0x156e29f0 is _alertController inside the instance of alert.
>>
>> Yes, the view controller class this is happening in is conforming to UINavigationControllerDelegate and I have set the self.navigationController.delegate to self.
>>
>> What I can't wrap my head around is why or how it is possible for something like this to happen.
>>
>>
>>
>> On Jul 29, 2015, at 2:08 PM, Alex Zavatone wrote:
>>
>>> I've got a completion block in an NSURLSessionDataTask that checks if the NSURLResponse statusCode is not 200 and in that case, it places a cell to a method to display a generic error message like so:
>>>
>>> // If no error occurs, check the HTTP status code.
>>> NSInteger HTTPStatusCode = [(NSHTTPURLResponse *)response statusCode];
>>>
>>> // If it's other than 200, then show it on the console.
>>> if (HTTPStatusCode != 200) {
>>> DLog(@"HTTP status code = %ld", (long)HTTPStatusCode);
>>> NSString *errorMessage = [NSHTTPURLResponse localizedStringForStatusCode:HTTPStatusCode];
>>> DLog(@"HTTP error message is: %@", errorMessage);
>>>
>>> // display error message;
>>> [self displayErrorMessage:errorMessage];
>>> return;
>>> }
>>>
>>>
>>> And in displayErrorMessage is will asks GDC to dispatch an async call to display the message on the main thread.
>>>
>>> // Error messages
>>> - (void)displayErrorMessage:(NSString *)errorMessage {
>>> DLog(@"<- ***");
>>> // handle on the main thread
>>> dispatch_async(dispatch_get_main_queue(), ^{
>>> NSString *internalErrorMessage = @"An error occurred. Please try again.";
>>>
>>> UIAlertView *alert = [[UIAlertView alloc]
>>> initWithTitle: nil
>>> message: internalErrorMessage
>>> delegate: nil
>>> cancelButtonTitle: @"OK"
>>> otherButtonTitles: nil, nil];
>>>
>>> if (alert) {
>>> [alert show];
>>> } else {
>>> DLog(@"For some reason, the alert instance isn't ready for a show.");
>>> }
>>> });
>>> }
>>>
>>> What's happening intermittently when I'm causing the server call to time out is that I'll get a bad access on the [alert show].
>>>
>>> I've spent all morning trying to narrow this down, to find out where the bad access is and why this is occurring. Sometimes in the stack trace, I'll see 3 or 4 calls to display the alert in different threads. Sometimes, I see that the [alert show] exception is being caused by navigationControllersupportedInderfaceOrientations: being sent to alert and the instruction pointer is on the [alert show line].
>>>
>>> I've included a screenshot of thread 1 to see if any of this makes any sense to anyone else.
>>>
>>> Thanks in advance if you're able to spend some time to help me out on this one.
>>>
>>> Adding an @try block around the [alert show] and retesting now.
>>>
>>> Stack trace screenshot below:
>>> http://i.imgur.com/KfILPLE.png
>>>
>>> - Alex Zavaotne
>>> _______________________________________________
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>>
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