Use of iOS Information interaction Protocol

If certain methods are defined in a protocol, and a class implements the protocol, the class must implement these methods. In other words, the protocol is a common set of method declarations, who implement the Protocol, who is responsible for implementing these methods, or there will be a yellow warning. The protocol can extend an existing protocol. The keyword for the agreement is protocol, starting with @protocol and ending with @end. When implementing a protocol in a class, you only need to add a < protocol name after the class name; Here's a look at the code:

Define a protocol first: Eat.h

[Plain]View Plaincopy

1. #import <Foundation/Foundation.h>
3. @protocol eat <nsobject>//protocol eat extended the protocol NSObject.h
4. -(void) eat;
5. @end

The above extended NSObject protocol is not implemented, because the class inheriting from NSObject has inherited the implementation of the NSObject protocol

Create a class below: Human.h

[Plain]View Plaincopy

1. #import <Foundation/Foundation.h>
2. #import "Eat.h"
3. @interface Human:nsobject <eat>
5. @end

Human.m

[Plain]View Plaincopy

1. #import "Human.h"
3. @implementation Human
4. -(void) Eat
5. {
6. NSLog (@ "eat defined in the agreement");
7. }
8. @end

Called in MAIN.M:

[Plain]View Plaincopy

1. #import <Foundation/Foundation.h>
2. #import "Eat.h"
3. #import "Human.h"
4. int main (int argc, const char * argv[])
5. {
7. @autoreleasepool {
8. Human *human =[[human alloc] init];
9. [Human eat];
11. }
12. return 0;
13. }

2012-03-18 14:35:29.099 category1[1752:403] defined in the agreement. Eat

Very simple, in addition, in the new version of the Objective-c, added some options for the protocol, @optional, @required, the protocol must be implemented in the method, otherwise it will be error, but if the @optional modified, there is no such restriction, The method that must be implemented by default is equivalent to a @required modification, such as the above code, and we can make the following changes:

Eat.h

[Plain]View Plaincopy

1. #import <Foundation/Foundation.h>
3. @protocol eat <nsobject>//protocol eat extended the protocol NSObject.h
4. -(void) eat;
5. @optional
6. -(void) Playguitar;
7. @required
8. -(void) sleep;
9. @end

In this case, the sleep method and the Eat method must also be implemented, and the Playguitar method is optional.

Use of iOS Information interaction Protocol