如何在特殊情况下

Question

访问一个NSArray计数我有块设置如下：

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

当我做呼叫：

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

我在看球员的数组。当我添加.count时，它找不到计数，因为它说count不是id的属性。我怎样才能访问这个数组的数量？

编辑：

这是我的整个数据块：

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：“*** - [__ NSArrayM objectAtIndex：]：指数17超越界限[0..16]'

Answer 1

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

然后你就可以访问count属性。