Is there any difference in how exceptions are handled under the hood between 'try?' and 'do/catch'?

[11ag11 (Agustin)]

I'm reviewing some errors, and I notice that some of them occur in JSONEncoder, where there's a 'try' and I have a 'do/catch' to catch the exception.
However, these errors don't reach the 'catch,' causing the app to crash.
My question is whether there's any difference between using a 'try?' that returns nil or using a 'catch'? Could it be that the error caught by 'catch' is different from simply returning nil? Or, beneath all this, is it exactly the same?
I'm not understanding why some errors aren't being handled, leading to the app's termination.
Thanks in advance. Regards.

[AronL (Aron Lindberg)]

I think the issue is that Swift can catch NSErrors thrown from Obj-C but JSONEncoder can also throw an NSException and that will crash your app even if you use try/catch when calling it from Swift.

There are workarounds, but none of them are great. I think a google search can give a better explanation than I can.

[xwu (Xiaodi Wu)]

@11ag11

My question is whether there's any difference between using a 'try?' that returns nil or using a 'catch'?

No difference in which errors can be propagated. If your app is crashing despite your code being in a do…catch block then it is not due to a recoverable error in that code.

[eskimo (Quinn “The Eskimo!”)]

However, these errors don't reach the catch, causing the app to
crash.

The issue here is that the term exception is horribly overloaded. I explains this in my What is an exception? DevForums post.

Share and Enjoy

Quinn “The Eskimo!” @ DTS @ Apple

[phoneyDev (Stern)]

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Catching NSException

Apologies if this has come up before - I've fallen behind in following this list. I recently ran into an issue where I needed to be able to catch NSExceptions raised by Objective C API in Swift, and found no good way to do that. Currently the only possible way is to via Objective C code that wraps the call in an Objective C style @try/@catch block. If building a swift framework, this means a separate module, since we can't use bridging headers. My quick attempt at a workaround can be s…

A tricky situation that the language seems to have no support for. (Exceptions, Extensions, Properties)

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Nothing has changed.

[tera]

@11ag11

I'm reviewing some errors, and I notice that some of them occur in JSONEncoder, where there's a 'try' and I have a 'do/catch' to catch the exception.
However, these errors don't reach the 'catch,' causing the app to crash.

Can you show a short self contained snippet reproducing the issue?