Ios 如何在特殊情况下访问nsarray计数

我已按如下方式设置了块：

    id block = ^(id obj, BOOL *ignored) 
{
  id data = [self.writer dataWithObject:obj];
  NSString *output = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];          
};

当我打电话时：

[[obj objectForKey:@"roster] objectForKey:@"players"];

我正在看一系列的球员。当我添加.count时，它找不到计数，因为它说计数不是id的属性。如何访问此数组的计数

编辑：

这是我的全部街区：

id block = ^(id obj, BOOL *ignored) {
                 id data = [self.writer dataWithObject:obj];

                 NSMutableArray *players = (NSMutableArray*)[[obj objectForKey:@"roster"] objectForKey:@"players"];
                 _players = [NSMutableArray array];

                 //Create player objects then add them to the array.

                 for (int i = 0; i <= players.count; i++)
                 {
                     [_players addObject:[HNPlayerObject newPlayerWithPlayerId:(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"id"])FirstName:(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"first"]) LastName:(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"last"]) Number:[(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"number"]) intValue] Team:@"Badgers" Position:@"Unknown" Description:@"" GamesPlayed:[(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"gp"]) intValue] Goals:[(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"g"]) intValue] Assists:[(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"a"]) intValue] Points:[(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"pts"]) intValue] PenaltyMinutes:[(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"pim"]) intValue] PlusMinus:[(@"%@",[[[obj objectForKey:@"roster"] objectForKey:@"players"][i] objectForKey:@"pm"]) intValue] IsPlaying:NO]];
                     [_playersTableView reloadData];
                 }

                 [_playersTableView reloadData];
             };

我收到此错误：“NSRangeException”，原因：“***-[\uu NSArrayM objectAtIndex:]：索引17超出范围[0..16]”

 NSArray *array = (NSArray*)[[obj objectForKey:@"roster] objectForKey:@"players"];

---

然后您就可以访问count属性。

我遇到了另一个问题，您可能可以帮助解决。请与我共享，以便我知道我是否可以这样做。