Does Objective-C support Generics?

Question

I wonder whether Objective-C offers any support for generics?

For instance, consider a method:

-(void) sort: (NSMutableArray *) deck {
}

Answer 1

Not directly, no. There a few ways to simulate it, but it requires a lot of wrapper code, boilerplate code, and runtime overhead. I just switch to Objective-C++ and use C++ templates when I want or need proper generics.

So if you wanted to introduce typesafety/checks to an NSArray, you could approach it using something like this:

template 
class t_typed_NSMutableArray {
public:
    t_typed_NSMutableArray() : d_array([NSMutableArray new]) {}
    ~t_typed_NSMutableArray() { [d_array release]; }

    /* ... */

    T* operator[](const size_t& idx) {
        T* const obj([this->d_array objectAtIndex:idx]);
        assert([obj isKindOfClass:[T class]]);
        return obj;
    }

    void addObject(T* const obj) {
        assert([obj isKindOfClass:[T class]]);
        [this->d_array addObject:obj];
    }

private:
    NSMutableArray * const d_array;
};

in use:

 t_typed_NSMutableArray array([self cards]); // < note this exact constructor is not defined

 Card * firstCard = array[0]; // << ok
 NSString * string = array[0]; // << warning

then you also get type safety and overloading when passing the collection, so you could not pass t_typed_NSArray as an t_typed_NSArray.