Bad things can happen when you don’t understand what you’re doing.
When writing my first iPhone application in Objective-C, I banged my head against the wall of memory management. EXC_BAD_ACCESS became a frequent and unwelcome guest during testing.
I have a C/C++ background, so picking up Objective-C was not particularly difficult. However, Objective-C objects are a different beast than I was used to. I soon noticed a theme while debugging my app; crashes happened around the words release and dealloc a lot.
I started sprinkling retains throughout my code, hoping to ward off the memory errors. Sometimes it worked, sometimes I created a leak, and sometimes the crash jumped somewhere else. It was like playing whack-a-mole. Bash a bug in one place, and it popped up in another.
The problem was, to me, Objective-C memory management was something magical. I created and deleted objects all the time, and usually it worked. But, I didn’t know the rules for when to retain. I was trusting the object fairies to know what I wanted to keep and what to whisk away.
Eventually, I stopped and said “There is something fundamental that I’m missing.” I spent an hour reading Apple’s Memory Management Programming Guide for Cocoa. It was like flipping on a switch in my head. I went back to my code, ripped out the useless retains, then picked off the bugs one by one.
Magical thinking is a recipe for disaster. You need to understand the tools you use. If something is a black box to you, take a crowbar and rip it open.
Don’t trust the fairies. They don’t take the support calls from your frustrated customers. Learn the magic yourself.
