Type id
The id
data type is used to store an object of any type. In a sense, it is a generic object type. For example, this line declares graphicObject
to be a variable of type id
:
id graphicObject;
Methods can be declared to return values of type id
, like so:
-(id) newObject: (int) type;
This declares an instance method called newObject
that takes a single integer argument called type
and returns a value of type id
.
The id
data type is an important data type used often in this book. We mention it in passing here for the sake of completeness. The id
type is the basis for very important features in Objective-C known as polymorphism and dynamic binding, which Chapter 9, “Polymorphism, Dynamic Typing, and Dynamic Binding,” discusses extensively. ...
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