[oc学习笔记]数组的遍历和排序

 1     //数组的遍历(可变数组举例) 2     //for遍历 3     NSMutableArray *aa = [NSMutableArray array]; 4     [aa addObjectsFromArray:@[@"ss",@"ddd",@"sad"]]; 5     for (int i = 0; i < aa.count; i++) { 6       NSLog(@"%@",[aa objectAtIndex:i]); 7     } 8     //快速遍历 9     for (id obj in aa) {10       NSLog(@"%@",obj);11     }12     //代码块遍历13     // obj是对象 idx是下标 stop是停止标志14     [aa enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {15       NSLog(@"%@",obj);16       NSLog(@"%@",[aa objectAtIndex:idx]);17     }];18     //迭代器遍历19     //将数组元素存放进迭代器20     NSEnumerator *en = [aa objectEnumerator];21     id obj = nil;//创建一个对象接受返回对象22     while (obj = [en nextObject]) {23       NSLog(@"%@",obj);24     }25     //反向迭代器遍历26     NSEnumerator *en1 = [aa reverseObjectEnumerator];27     id obj1 = nil;28     while (obj1 = [en1 nextObject]) {29       NSLog(@"%@",obj1);30     }31     32     33     //排序(可变数组举例)34     //可变数组排序的方法无返回值 不可变数组的排序有返回值35     //选择器排序36     //compare方法尽限于比较元素是字符时 ，如有另外的比较 请另写比较方法 返回值（NSComparisonResult）37     [aa sortUsingSelector:@selector(compare:)];38     //代码块排序39     //根据实际情况写判断方法40     [aa sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {41       return [obj1 compare:obj2];42     }];43     //比较描述器排序44     //对多个条件进行排序比较便利45     Person *p1 = [[Person alloc]init];46     p1.name = @"ss";47     p1.age = @"16";48     49     Person *p2 = [[Person alloc]init];50     p2.name = @"dd";51     p2.age = @"14";52     53     Person *p3 = [[Person alloc]init];54     p3.name = @"hh";55     p3.age = @"22";56     57     Person *p4 = [[Person alloc]init];58     p4.name = @"hh";59     p4.age = @"19";60     NSMutableArray *sss = [NSMutableArray arrayWithObjects:p1,p2,p3,p4,nil];61     NSSortDescriptor *sort1 = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];62     NSSortDescriptor *sort2 = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];63     NSArray *s = @[sort1,sort2];64     [sss sortUsingDescriptors:s];65     NSLog(@"%@",sss);

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原标题：[oc学习笔记]数组的遍历和排序

关键词：排序