Protocol protocol Use

Protocol protocol:

The protocol is similar to the interface in C #

L used to declare the method

L if a class complies with an agreement, then it has all the statements of the agreement.

L can comply with multiple protocols

As long as the parent adheres to a protocol, the subclass adheres to that protocol.

Comply with the agreement <,>

Inheritance by:

1. Protocol Definition

@protocol protocol Name

@required//Require implementation, do not implement will issue a warning

-(void) test;

@optional//Do not need to implement

-(void) test2;

@end

2. How to comply with the agreement

1> Class Compliance Agreement

@interface Class Name: Parent class < protocol name,......>

Base agreement: Any agreement is subject to that agreement <NSObject>

L A protocol that complies with another agreement can have all the method declarations of this Agreement

2> Protocol Compliance Agreement

@protocol Child protocol name < Parent protocol,........>//Much like inheritance in a class but not inheritance

Limit the object type when you top a variable and follow a protocol

nsobject< protocol name > *obj = Class of Compliance protocol

Requires Obj5, the saved object must obey Myprotocol3, and inherit the person

Person<myprotocol3> *person;

Protocol protocol Use