Objective-C++ object type helpers

helpers.hpp

template<typename T>
struct remove_ownership {
    using type = T;
};

template<typename T>
struct remove_ownership<__strong T> {
    using type = T;
};

template<typename T>
struct remove_ownership<__unsafe_unretained T> {
    using type = T;
};

template<typename T>
struct remove_ownership<__weak T> {
    using type = T;
};

template<typename T>
struct remove_ownership<__autoreleasing T> {
    using type = T;
};

template<typename T, typename U>
T *objc_dynamic_cast(U *value) {
    if ([value isKindOfClass:[T class]]) {
        return (T *)value;
    }
    return nil;
}