//NSArray 自然顺序        //NSSet是无序的        //注意:这个是最为重要的功能 NSSet中不能够存储重复的数据,可以用它来去除重复的值        NSString * str1 = @"one";        NSString * str2 = @"two";        NSString * str3 = @"three";        NSSet * set = [[NSSet alloc] initWithObjects:str1,str2,str3,str1, nil];        NSLog(@"set %@",set);                //count        NSLog(@"count %ld",set.count);               BOOL isContains =  [set containsObject:str1];        if (isContains)        {            NSLog(@"YES");        }        else        {            NSLog(@"NO");        }                //4.遍历                NSEnumerator * enumerator = [set objectEnumerator];        NSString * value;        while (value =http://www.mamicode.com/ [enumerator nextObject]) {            NSLog(@"value %@",value);        }

NSString * str1 = @"one";        NSString * str2 = @"two";                //1 创建一个可变集合        NSMutableSet * muSet = [[NSMutableSet alloc] init];                //2.增加值        [muSet addObject:str1];        [muSet addObject:str2];                NSLog(@"muSet %@",muSet);                //3.删除        [muSet removeObject:str1];                NSLog(@"muSet %@",muSet);                //4.删除所有//        [muSet removeAllObjects];            NSLog(@"muSet %@",muSet);                //5.遍历        NSEnumerator * en = [muSet objectEnumerator];        NSString * value;        while (value =http://www.mamicode.com/ [en nextObject]) {            NSLog(@"value %@",value);        }