Objective-C quantity type-objective-c id data type

ID data typeAny type of objects can be stored. In a sense, it is a common object type. For example,ProgramLine

ID number; Declare number ID type. You can declare a method to make it return values of the ID type, as follows: -(ID) newobject: (INT) type; This program line declares an instance method named newobject, which has a single integer parameter named type and a return value of ID type. It should be noted that for the return value and parameter type declaration, IDYes Default. Therefore, the following program lines: + Allocinit; Declares a response ID type. ID typeIt is a very important data type in objective-C. It is the basis of polymorphism and dynamic binding, which will be frequently used in future Apple development.