Mark designated initializer at compile time

gistfile1.m

#define MSDesignatedInitializer(__SEL__) __attribute__((unavailable("Invoke the designated initializer `" # __SEL__ "` instead.")))

// Sample usage:

- (instancetype)initWithObject:(id)object;
- (instancetype)init MSDesignatedInitializer(initWithObject:); // <- This even gets auto-complete.

// Now calling init on this class would throw a warning.

@haemi You would probably have to mark + (instancetype)new in the same manner.