Patrick is basically not correct. void, int, bool are not headers neither should you focus your search through dumped headers on the data types
There are no newer methods. Flex is really old and so is IDA,they always were options.
They are very obvious. If you want to find the debug menu it's probably -(bool) enableDebugMenu or -(bool) showDebugMenu. Also I'm impressed by the number of wrong syntax in that code block: I'm counting 4
1. [ ] are not used here and will never be in this context
2. (+BOOL) is +(BOOL) or rather -(BOOL)
3. The method name always starts with a small letter thus Debugmenu won't work
4. You put ; at the wrong position in the return statement