xcode for iOS中的异常断点是可以原谅的例外吗？

Question

Am new to the iOS development. While looking into one of the App I work on, with exception breakpoint enabled in xcode . I see so many repetitive exceptions been raised.

But till now, we never realised this, as iOS was excusing those exceptions. The main exception was happening in our service layer, where, in an XML parsing, one of the element mentioned as key was missing. since so many back end requests are fired, for every XML response, and for multiple items inside it, this exception is thrown.

Now that our app is published, will this impact the device's stability? We are planning to fix thee kind of issues. But now, Will these be logged into Apple's diagnostic information. Just curious to know these. Can someone shed some light over it?

Answer 1

In Objective-C, Exceptions are used to signal fatal errors, that is programmer errors and "unexpected" and unrecoverable runtime errors. In Objective-C, Exceptions are a debugging and testing aid, not a construct to control program flow or to regain control after an error.

Usually, an application in a release state shouldn't throw exceptions. If it happens anyway, the only correct course of action is to terminate the program as soon as possible. In general, the Objective-C system frameworks are not exception safe . This means, after an exception has been thrown the application's state will be corrupt. If your program continues, even worse things may happen.

There are only a few, always undocumented harmless cases where exceptions will be thrown and caught by system libraries without leaving the program in an unstable condition.

See also https://developer.apple.com/library/ios/documentation/cocoa/conceptual/Exceptions/Exceptions.html