Fix crash: firstObject is more secure because it returns nil

[asam139]

In some situations the framework crashes because the dispatch is asyncrhonous and it is accesing to the object with zero index, so to fix it it is better to use "firsObject" method because it returns nil and it does not crash.

[isadon]

The pull request has not been merged, even though above it states it was..

Not sure why a crash is being generated when accessing a 0 index of an array. Above the 0 index access there are condition (if checks) that make sure the array has at least one object.. Can you give more details about the crash you are getting and why accessing via firstObject solves it?

[asam139]

Here you has the explication about firstObject or objectAtIndex: Post

If you don't want to use firstObject you must do the check inside of the dispatch because it is asynchronous and it can crash.

Although for me, it is cleaner to use the "firstObject" method.

Here you can see the crash in Fabric of the app which I work.

Thanks you so much for your time!! :)

[isadon]

The link you posted is no longer working. When I did read it though I don't believe it was sufficient to explain the reasoning why firstObject should be used and how it ties in to the need to use it in the async call. Can you provide steps to reproduce? How exactly is the crash being generated?

[asam139]

I fixed the link if you want to read it. If I find the steps to reproduce it, I communicate you 👍

[isadon]

As far as the link you posted I understand why a direct access to the array element index 0 results in a crash when the array is empty. firstObject returns nil and prevents a crash. But that wouldn't solve the true problem which is reproducing how the array becomes empty in the async call but not right before the async call in the "if" check. Definitely let me know if you can reproduce the issue.

[isadon]

I believe the issue lies in that the dismissNotification method is not thread safe. If multiple messages are displayed and then auto dismissed the timing of the dismiss notifications may possibly lead to a crash. I haven't completely verified this yet but expect an update soon.

[isadon]

Can you please try the develop branch and tell me if you still get the crash or can reproduce?

[asam139]

ok, I am going to use develop branch and if I can reproduce the crash I will tell you :)

[isadon]

also test the regular master branch.. there were some slight modifications there as well that "may" have solved the crash.