LHF Objective-C语法（8）协议

Printing.h @protocol Printing1-(void)print1;@end@protocol Printing2-(void) print2;@end@protocol Printing3<Printing2>-(void)print3;@end

1、objc里的协议与java中的接口是同一个东西

2、协议可以遵从协议

2、说法：类Fraction遵从了Printing1、Printing3   

//Fraction.h================================#import <Foundation/Foundation.h>#import "Printing.h"@interface Fracion : NSObject<Printing1,Printing3>{ int numerator; int denominator;}-(Fraction*) initWithNumerator:(int) n denominator:(int)d;-(void) setNumerator:(int) n;-(void) setDenominator:(int) d;-(int) numerator;-(int) denominator;@end//Fraction.m================================#import "Fraction.h"@implementation Fraction-(Fraction*) initWithNumerator:(int) n denominator:(int)d{ self = [super init]; if(self){ [self setNumerator:n]; [self setDenominator:d]; }}-(void) setNumerator:(int) n{ numerator = n;}-(void) setDenominator:(int) d{ denominator = d;}-(int) numerator{ return numerator;}-(int) denominator{ return denominator;}-(void)print1{ NSLog(@"1:%d/%d",numerator,denominator);}-(void)print2{ NSLog(@"2:%d/%d",numerator,denominator);}-(void)print3{ NSLog(@"3:%d/%d",numerator,denominator);} main.m

//main.m================Fraction *frac = [[Fraction alloc] initWithNumerator:3 denominator:5];<Printing1> p1 = frac;//id<Printing1> p1 = frac;[p1 print1];id<Printing1,Printing2,Printing3> p2 = frac;[p2 print2];[p2 print3];//用于判断对象是否遵从某个协议if([frac conformsToProtocol:@protocol(Printing1)] &&([frac conformsToProtocol:@protocol(Printing2)] &&([frac conformsToProtocol:@protocol(Printing3)]){ NSLog(@"YES"); }else{ NSLog(@"NO"); }[frac release];return 0;