Passing Object Pointers Between Objective C and C under ARC

Under ARC (Automatic Reference Counting), there are some things to note when passing pointers between Objective C and C codes.

When passing Objective C object pointer to C function:
    void* cptr = (__bridge void*)objcptr;

And back
    ObjCClass *objcptr = (__bridge ObjCClass*)cptr;

References

• http://stackoverflow.com/questions/6868130/implicit-conversion-of-an-objective-c-pointer-to-void-is-disallowed-with-arc
• http://clang.llvm.org/docs/AutomaticReferenceCounting.html#objects.operands.casts
• http://stackoverflow.com/questions/7036350/arc-and-bridged-cast