I know how to create my own arduino library and use it. I am using Xcode to create a c++ project. I have the arduino library files(Servo, Wire, Keypad, etc). If I want to include the Servo.h library file in my created library, how do I go about linking that? For some reason, I can't just add the Servo.h/.cpp files in my project because then I get other linking file problems that Servo.h references and are not linked in my project. Has anyone done this before?
I can't speak for Xcode, but in general with Arduino IDEs (UECIDE excepting) if you use a library within another library, that library also has to be #included in the main sketch. That is the only way most IDEs determine which libraries need to be compiled into the finished program.
That's one of the first targets I had for UECIDE - to enable fully recursive library compilation. Any libraries found within the master header of a library will also be included for compilation - and any found in those libraries, etc. It took a lot of work (and it's by no means 100% perfect), which is why so few others do it and leave it up to the programmer to ensure the inclusion of the right sub-libraries in their sketch.