由于未捕获的异常“NSRangeException”而终止应用程序，原因：“*** -[__NSArrayM objectAtIndex:]：索引 0 超出空数组的范围”

Question

我正在使用 Web 服务开发应用程序时遇到这样的错误，它是在我测试真实设备时发生的，但是当我运行视网膜 3.5 模拟器时，它运行良好，请帮助我，我已经尝试过，但我无法解决这个问题。

Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'
*** First throw call stack:
(0x30b59fd3 0x3b308ccf 0x30a9081b 0xeec19 0x334a8917 0x3344fc47 0x3344f49d 0x33375d79 0x32ff362b 0x32feee3b 0x32feeccd 0x32fee6df 0x32fee4ef 0x33379401 0x30b2525b 0x30b2472b 0x30b22f1f 0x30a8df0f 0x30a8dcf3 0x35992663 0x333d916d 0x100ec1 0x3b815ab7)
libc++abi.dylib: terminating with uncaught exception of type NSException

代码：

-(void)loaddetails
{
    NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://api.espn.com/v1/sports/football/news/headlines?apikey=th98vzm67pufc36ka42xxxmy"]];
    [request setHTTPMethod:@"GET"];
    [request setValue:@"application/json;charset=UTF-8" forHTTPHeaderField:@"content-type"];
    NSError *err;
    NSURLResponse *response;
    NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&err];
    NSDictionary *jsonArray=[NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:&err];

    NSArray *headlinetop=[jsonArray objectForKey:@"headlines"];

    for (int i=0; i<[headlinetop count]; i++)
    {
        NSString *headstr=[[headlinetop objectAtIndex:i]objectForKey:@"headline"];
        [loadingcell addObject:headstr];
    }
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

    static NSString *CellIdentifier = @"cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:nil];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] ;

    }
    UILabel *title = [[UILabel alloc] initWithFrame:CGRectMake(10, 10.0, 250, 26.0)];
    title.backgroundColor = [UIColor clearColor];
    title.textAlignment = NSTextAlignmentLeft;
    title.textColor=[UIColor blackColor];
    title.font = [UIFont fontWithName:@"Arial Hebrew" size:15.0];
    title.text=[loadingcell objectAtIndex:indexPath.row];
    [cell.contentView addSubview:title];
    if ([[UIDevice currentDevice]userInterfaceIdiom]==UIUserInterfaceIdiomPhone) {
        cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
    }


    return cell;
}

Answer 1

为了理解访问数组对象的概念，这里我想出了一个例子，它清楚地解释了为什么当你访问数组中的索引处的对象时它会崩溃。

我不会指出你在哪里犯了错误。理解这个概念并在此基础上更改任何你有的代码，比如[yourArray objectAtIndex:10]。

非软件示例：

你有 bag(NSMutableArray) ，它有 10 个标记为 (0,1,2...9) 的球，但是你如何找出第 11 个球。不可能！。

1.首先你应该准备好手上的包。([[NSMutableArray alloc] init])

2.然后尝试访问它。

3.您的问题是您正在寻找袋子内的第一个球（第 0 个标记）。 iOS 说“对不起”

//assume [array count] == 10 (0,1,2,3,4,5,...9)

NSUInteger indexTobeAccessedInArray = 5;//6th object (0,1,2,3,4,5,...9)


if (array && [array count]>0) {
    // array lives in memory and it has atleast one objects in it

    // 5 < 10
    if (indexTobeAccessedInArray < [array count]) {
        //Yes
        NSLog(@"you can access this index:%i",indexTobeAccessedInArray);

    }
    else{
        //No
        NSLog(@"Index %i beyond bounds for array",indexTobeAccessedInArray);

    }

}
else{
    // There was no array in memory
    NSLog(@"sorry there is no array, you should create & initialize it first like \n NSMutableArray *array = [[NSMutableArray alloc]init]");

}

Answer 2

你可以试试：

id myObject = [myArray firstObject];
if(nil != myObject)
{
    // Do something
}

但是如果不向我们展示代码，我真的无法再提出建议了。

Answer 3

您可以使用行数委托方法来解决问题。如果 loadingcell 数组为空。然后单元格将加载空行..

loadingcell=[[NSMutableArray alloc]init];//check that you initialized and allocated loadingcell

如下修改你的代码..

 - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
     {
        return loadingcell.count;
      }

    -(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
    {

        static NSString *CellIdentifier = @"cell";

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:nil];

        if (cell == nil) 
        { 
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] ;

        }
        if(loadingcell.count>0)
        {
          UILabel *title = [[UILabel alloc] initWithFrame:CGRectMake(10, 10.0, 250, 26.0)]; title.backgroundColor = [UIColor clearColor]; 
          title.textAlignment = NSTextAlignmentLeft; 
          title.textColor=[UIColor blackColor]; title.font = [UIFont fontWithName:@"Arial Hebrew" size:15.0]; 
          title.text=[loadingcell objectAtIndex:indexPath.row]; 
          [cell.contentView addSubview:title]; 
          if ([[UIDevice currentDevice]userInterfaceIdiom]==UIUserInterfaceIdiomPhone) 
          { 
             cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator; 
          }
        }

        return cell; 
   }

希望对你有帮助..