OBJECTIVE-C Protocol Protocol

 Everything is possible.

the protocol defines a set of methods for other classes to implement. The protocol itself is not a class. a protocol is a set of methods that are not implemented. A protocol is a group that has a certain correlation. the methods in the Protocol are implemented by other people

//
// main.m

#import <Foundation / Foundation.h>

#import "Student.h"

int main (int argc, const char * argv []) {
    @autoreleasepool {
        // insert code here ...
        NSLog (@ "Hello, World!");
        Student * stu = [[Student alloc] init];
        [stu finishTeask];
        [stu dontlate];
        [stu wearNeat]; // optional
   
    }
    return 0;
}
 

All default methods in the protocol must be implemented
The agreement has two keywords: @required and @optional
@required indicates the methods that must be implemented
@Optional means optional implementation
//
// Scsy.h

#import <Foundation / Foundation.h>
// protocol Scsy protocol <parent class>
@protocol Scsy <NSObject>
@ required // must be implemented
//statement
//finish homework
-(void) finishTeask;
//Do not be late
-(void) dontlate;
@ optional // optional
// Clean clothes
-(void) wearNeat;
//
// Student.h

#import <Foundation / Foundation.h>
#import "Scsy.h"
@interface Student: NSObject <Scsy>

@end
//
// Student.m

#import "Student.h"

@implementation Student
-(void) finishTeask {
    NSLog (@ "complete job");
}
-(void) dontlate {
    NSLog (@ "Cannot be late");
    
}
-(void) wearNeat {
    NSLog (@ "衣衣 tidy");
}
@end 

OBJECTIVE-C Protocol Protocol