Casting a basic CFTypeRef to a more specific CoreFoundation type

Is there a simple way to convert开发者_Go百科 a CTypeRef to a specific CoreFoundation type? I'm not looking to cast inline as (CFStringRef)myObjectRef but would like to create a helper method to do this for me for all CoreFoundation types.

I know it's possible to use something like CFGetTypeID(myObjectRef) == CFStringGetTypeID() to find out whether a CTypeRef is a CFString. However creating a single method to do this could become very verbose and have a lot of if statements.

Is building out a method with a bunch of if statements against CFGetTypeID() the only way? Or is there a simpler way to do this?

UPDATE: with example

I'd like to make a helper function to work with some legacy code I can't change. Currently it produces one of CFDictionaryRef, CFStringRef or CFURLRef as a return value provided as a CTypeRef. I'm currently working around this by running CFGetTypeID() on the returned value but this isn't ideal. Rather than having C-style casts all over the place, I'd rather have a CastToCF() helper which handles this for me. This would help make testing easier in the future as well.

P.S. I'm not worried about mutable types.

there's no obvious point in doing this. a c style cast is not like other languages - it is a typecast which the address on the left will be identical to the address on the right. cftypes will not throw or return null if you do a bad cast (unlike other languages). iow, it's merely a decoration for you to specify a type, and a c compiler will assume your cast is valid.

or perhaps you can provide a better example of how you would use this, if that did not help.

Update

ok. since you tagged it objc++, i'd just create a helper class which had plenty of diagnostics and did all the noisy conversions (minimal illustration):

class t_helper {
public:
    t_helper(CFTypeRef cf) : d_cf(cf), d_type(CFGetTypeID(cf)) { assert(this->d_cf); }
    ~t_helper() {}

    /* type info */
    bool isString() const { return CFStringGetTypeID() == this->type(); }
    CFStringRef string() { assert(this->isString()); return this->cf_cast<CFStringRef>(); }

    bool isDictionary() const { return CFDictionaryGetTypeID() == this->type(); }
    CFDictionaryRef dictionary() { assert(this->isDictionary()); return this->cf_cast<CFDictionaryRef>(); }

 ...

    /* and a trivial example of an operation */
    void appendMutableCopyToArray(CFMutableArrayRef array) {
        if (this->isString()) {
            CFMutableStringRef cp(CFStringCreateMutableCopy(0,0,this->string()));
            CFArrayAppendValue(array, cp);
            CFRelease(cp);
        }
        ...
    }

 ...

private:
    template < typename T > T cf_cast() { return reinterpret_cast<T>(this->d_cf); }
    const CFTypeID type() const { return this->d_type; }
private:
    CFTypeRef d_cf;
    const CFTypeID d_type;
};

that's about as accurate as i can get get without a really specific example of the program you are dealing with.