I have an iPhone app with a secondary thread to handle XML parsing. Inside some of those methods, I need to reference dictionaries (for look up, not modification) created and populated in the main thread.
Apple's documentation indicated to me that global variables might be the best way to accomplish this. I'm just now sure what the implementation would look like. Define the dictionaries at the top of .m and access them normally inside the secondary thread?
NSDictionary is thread-safe, so it's probably not a threading issue unless your initializer allocates the global as an NSMutableDictionary (not thread-safe) and then the secondary thread tries to access it while it's still being populated.
(If this is the case, your initializer should first allocate the NSMutableDictionary into a local variable, populate it, then copy the finished local to the global using NSDictionary's +dictionaryWithDictionary: or -initWithDictionary:.)
Alternatively, could it be that you're not retaining the global when initializing it?