Question

i want to convert id* to NSNumber *

trying this
unsigned int ShortValue = [(NSNumber *)idObject unsignedShortValue];

but this aint compiling

Cast of an indirect pointer to an Objective-C pointer to 'NSNumber *' is disallowed with ARC

any ideas how to do it.
basically id* object will be argument to my method ,second argument will be type information of this id* object then inside this method i am performing type specific methods on it like one above

Answer 1

id is a semi-primitive type, as it is declared in objc.h as

typedef struct objc_object {
    Class isa;
} *id;

When you create id objects, you don’t use an “*”, as that is for pointers to objects, so basically don’t do this:

id *someObject;

The correct syntax would be this:

id someObject;

Hope this helps!

——–EDIT——
I tried out the code you used:

unsigned int ShortValue = [(NSNumber *)idObject unsignedShortValue];

and it compiled fine. I think the error is how you create idObject.

———EDIT———

Here’s an apple doc on id: http://developer.apple.com/library/ios/#documentation/cocoa/conceptual/objectivec/Chapters/ocObjectsClasses.html
and here’s two good resources on the isa pointer: What does isa mean in objective-c?, http://cocoasamurai.blogspot.com/2010/01/understanding-objective-c-runtime.html. In the second link, scroll to the top third of the article to find info on isa*. Hope this helps!