How to check if an id points to a CGRect?

Question

Supposing we have:

id value = [self valueForKey:@"frame"];
BOOL valueIsCGRect = ???;

How can I decide? Should I cast id to something?

Answer 1

The returned value will be of type NSValue for scalar types, which provides the method objCType, which returns the encoded type of the wrapped scalar type. You can use @encode() to get the encoding for an arbitrary type, and then compare the objCType.

if(strcmp([value objCType], @encode(CGRect)) == 0)
{
   // It's a CGRect
}