Question

I’ve been experiencing a weird error in my Objective-C program for iPhone. Here’s what happens:

• I get a EXC_BAD_ACCESS crash.
• Fine, the zombies kick in and the log tells me it’s about a CFNumber that gets a release, but is already deallocated. Still no tough cookie.
• I keep debugging until I hit a block with two NSNumbers. There are no CFNumbers in my code, so I reckon it’s these lines.
• I try retaining them, with no success, even filling them with nil, overwriting them with new values, etc. Still nothing.
• I comment the lines out. Now the log keeps bugging about the same CFNumber, but now is being sent a “doubleValue” (instead of “release”) while it’s already deallocated. There is no “doubleValue” in my code.

What’s going on here? Are the zombies messing with my code? I’m on a dead end here. Any help is greatly appreciated.

Kind regards,

Reinder

Answer 1

Sadly, not much we can do without code.

Here are some general principles to keep note of, and will make your life easier.

You refers to the current class.

• if you need to use it for a long period of time, retain it.
• if you don’t need it at the end of a function, don’t keep it (alloc, then release at the end) if you did not retain it, do not release it.
• if you did not alloc it, do not release it.
• if you are returning an object you allocated, and thus will lose control of it, autorelease (pretty much what it was designed for). This is in line with principle 3 and 4, as it means the calling class will need to make the decision to retain or release it.

Hope this helps you pinpoint the problem.