OC中用协议实现的多继承

#import <Foundation/Foundation.h>

@protocol Add <NSObject>
- (int)addA:(int)a b:(int)b;
@end

#import <Foundation/Foundation.h>

@protocol Sub <NSObject>
- (int)subA:(int)a b:(int)b;
@end

#import <Foundation/Foundation.h>

@protocol Mul <NSObject>
- (int)mulA:(int)a b:(int)b;
@end
==================================================以上是三个协议
下面是新建一个继承与NSObject的计算类Calculator
#import <Foundation/Foundation.h>
#import "Add.h"
#import "Sub.h"
#import "Mul.h"

//遵守多个协议
//类似于c++的多继承
@interface Calculator : NSObject <Add,Sub,Mul>

@end

#import "Calculator.h"

@implementation Calculator
- (int)addA:(int)a b:(int)b {
return a+b;
}
- (int)subA:(int)a b:(int)b {
return a-b;
}
- (int)mulA:(int)a b:(int)b {
return a*b;
}
@end
==========================================
#import <Foundation/Foundation.h>
#import "Calculator.h"

/*
现在有多个类，一个是加法器类（会算加法） 第二个类是减法器类（减法功能）第三个乘法器类（乘法）

实现一个类分别可以进行+-

c++可以用多继承实现

但是OC没有多继承 但是OC可以通过协议来实现
*/

int main(int argc, const char * argv[]) {
@autoreleasepool {
Calculator *calc = [[Calculator alloc] init];

NSLog(@"%d",[calc addA:1 b:1]);//2
NSLog(@"%d",[calc subA:1 b:1]);//0
NSLog(@"%d",[calc mulA:1 b:1]);//1
}
return 0;
}