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Just found a nasty crash with NSZombiesEnabled. A deallocated view was called with performsSelector. huh? who did this?

Turns out that’s a corner case, scrolling was not yet done (because animated) but due to low mem the view was discarded instantly. Then system called the view: hey, done with scrolling! kaboom.

So, rule of thumb: clear your delegates on viewWillDisappear and re-set them  on view WillAppear. No more troubles.

Thanks again, StackOverflow (a but cryptic this time)

Google’s not very helpful on this error. NSInternalInconsistencyException ‘Attempt to create two animations for cell’

After banging my head against the wall several times, I got the solution – and how simple it is! I’ll post the full code here.
In short, remember all your insert/update/delete operations and make sure only one animation per cell is called.
Remember this is three20 code, and you’ll need the willUpdateFor- functions in the DataSource. This overrides code from three20’s internal sources.
Update: changed dictionary to set.

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Missing namespaces are a a huge problem in objectivec – something that can’t be solved easily. And the more third-party libs you use, the more trouble it gets.

Imagine, I had to rename my model classes after linking with the MessageUI Framework (InApp Email) because “Message” and “Account” classes are used by Apple. Private ones, not documented, but there. And they conflict with your classes, at least if you use Core Data.

Lesson learned: prefix everything!  (There’s a reason it’s NSString, not String, or CFRect, not Rect…)

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