Consistent error and exception reporting (PFParameterAssert usage)

[moflo]

Hi, thank you for opening this code base up & good work! We occasionally get stuck with runtime exceptions which are difficult to debug. Having centralized error and exception mechanism should help, but your code currently uses a mix of PFParameterAssert macros, NSAssertions and ad-hoc error reporting. Could you perhaps use PFParameterAssert throughout so we have a central point to trap all exceptions?

For example, these calls to NSAssertion could be converted to the PFParameterAssert (or similar) macro: https://github.com/ParsePlatform/Parse-SDK-iOS-OSX/search?utf8=✓&q=NSException&type=Code

Finally, any chance we could see the error codes in PFConstants aligned with the error & exception reporting: https://github.com/ParsePlatform/Parse-SDK-iOS-OSX/blob/61f68e9333206f0eebf15d5adab076a0ae7c4b71/Parse/PFConstants.h#L151

Thanks!

[nlutsenko]

It's a great point!

The thing with asserts vs errors is that asserts are meant to be a very early indication of a programmer mistake vs something that could go wrong along the line (no network connection or server settings changed).

We are consistently iterating over to convert low-signal asserts (exceptions) to errors, but it's going to take a little bit of time to get there. Would be great to get some feedback on specific assertions that are not useful and having an error instead would be more helpful.