My game is done, but I upgraded to 1.5 to see if it would improve my game speed.
Now my game won’t even start…
How can I downgrade to the previous version of Unity?
You should probably just figure out what’s wrong with the 1.5 build of your game. It’s probably something simple.
Maybe if you shared any error messages you are getting?
Also, this kind of thing is exactly what Time Machine is for. Backup, backup, backup!
That’s the problem. I’m not getting any error messages.
Yeah well, I bought a drive to use with Time Machine, just never turned it on…
You can actually install both side a side.
Rename the unity iphone folder to unity iphone 1.5 and then install the last 1.0.x version to use it there again.
Also if it just does not work: Do you get a sigbus error?
If so, is the Bliprob enhancement kit in, cause if the answer is yes, kick it out until the 1.5 compatible one is around. There are some problems with it that will kill your app on startup.
Okay, I’ll try to re-download it from Unity’s site.
No error at all. The game acts ‘quirky’ in the editor, and won’t load past my load screen on the iPhone.
Don’t have the enhancement kit. It looks interesting, but didn’t have a need for it on my first project.
a game can not hang without showing an error when started in debug in XCode.
it will show clearly what calls lead to the crash and what kind of crash it is.
the only exception is if you forgot about the basic requirements for iphone games like the “max acceptable nonresponsive time” which is 20s by now I think. After that time of unresponsiveness, the iphone os will just kill your app so never come up with loading into a game level when starting the app, thats granted to never get anywhere 
I’ve had large apps that on first load take 24 seconds to load on the older devices. Second time around, its roughly 8 or 9.
Of course, a quick loading screen is worth the effort 
that it restarts faster is thanks to apple not following their hot air about the iphone os.
if the sandbox would really work as it has been advertised since day 1:
- The crashes would have far less regularily
- apps wouldn’t start faster after first crash
- free memory wouldn’t be required to clean the memory mess generated by those damned installer demons of iphone os
@tony - are you sure you don’t have deprecated stuff like positionDelta or timeDelta? Those would show in the editor console. Make sure you don’t have collapse on in the console if you’re not looking at the console window. Just a thought…
Oh, I’ve got tons of Time.deltaTime. Are you saying that no longer works?
Pete said “timeDelta” - there would be real problems if they had deprecated Time.deltaTime
I now know what was keeping the game from loading…
It was an error with PlayerPrefs. On first run, it tried to load a non existent preference and must have given me an exception.
Not sure, but this might be some kind of bug in 1.5, as my game ran fine before the update.
Still, it was an easy enough fix, I just checked to see if the key existed and if not, initialized the value.
I’m still going to downgrade, because I’m not seeing any speed improvement and 1.5 introduced some quirks to my game I’d rather not deal with (such as sounds randomly not starting, static variables behaving strangely, etc.)