Add nullability specifier to all pointers in ZLPeoplePickerViewController.h

[king7532]

This will help when using this project in a Swift app :)

Ideally all the header files should be updated to include nullability specifiers for all pointers to eliminate the compiler warnings [-Wnullability-completeness].

Here's a great blog article on it:
https://developer.apple.com/swift/blog/?id=25

[zhxnlai]

Thanks for pointing this out! Let me add you as a collaborator.

[king7532]

Thank you!

[king7532]

I was hoping that since you have more knowledge of the codebase that you could add the nullability specifiers for the ZLPeoplePickerViewController.h now and then I'll start adding them as I get more familiar this project. I'm hoping to ship my app with this project in the next few weeks. Thanks again!

[zhxnlai]

Sorry for the late reply! I am really excited that you found this project useful but it has been six months since I last worked on it. I will do my best to help making it better.