Few 64 bit conversion points to take care of

Specifically take care of the following

 

·         Allocate Memory Using sizeof

Never call malloc with an explicit size (for example, malloc(4)) to allocate space for a variable. Always use sizeof to obtain the correct size for any structure or variable you allocate. Search your code for any instance of malloc that isn’t followed by sizeof.

·         Always Define Function Prototypes

·         Take Care with Functions and Function Pointers

 

Here are more details on that

https://developer.apple.com/library/ios/documentation/General/Conceptual/CocoaTouch64BitGuide/ConvertingYourAppto64-Bit/ConvertingYourAppto64-Bit.html