Header files are a blessing. They move many bugs from runtime to compile time. The point of the header file is to make a contract. Sometimes that isn't appropri

Header files are a blessing. They move many bugs from runtime to compile time. The point of the header file is to make a contract. Sometimes that isn't appropriate and there you can "go dynamic" if you need to, but you are moving your errors to the runtime. The retain/release model of object lifetime management in Objective C becomes nearly automatic for the programmer. That being a dangerous "nearly", you can still screw up. Garbage collection is much nicer, but given the limited memory I can understand why they didn't enable it on the phone. Remember: You can screw up badly with garbage collected systems too, it just doesn't result in a core dump on a desktop machine. You can accidentally leave references to objects you will never access again (cache structures are notorious) preventing it from being reclaimed. On a desktop that leads to a bit of memory bloat and maybe some swapping if the app runs long enough. On an iPhone you run out your RAM and get terminated.