After migrating from XCODE 4 to 4.2 i have quite a few problems with my applications, many of them due to my own bad code quality.
As an example i had for some reason done two calculations looking like:
xx = xx++
...which worked in XCODE 4 but not in 4.2 where the compiler jumped over and did not either process or warned about it. This took me a week to find&fix even if i tried to read-up on the differences between 4 and 4.2.
Changed it to:
xx++
..so it works now :-)
However, i still have problems so i wonder if someone could point me to where i can read about these type of "smaller but important" differences, which hopefully can help me track the other issues down.
Cheers