Question

我是xcode的新手，我需要帮助。

我有这个json：

{
    "noticias": [
        {
             "titulo":"teste"
        }
        {
             "titulo":"teste 2"
        }
    ]
}

我是如何得到结果的？我试过了

NSDictionary *not = [noticias objectAtIndex:indexPath.row];

但我收到错误，因为我有关键的“noticias”

更新：这是根据到目前为止收到的答案尝试的代码。我有这个：

- (void)fetchNoticias
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData* data = [NSData dataWithContentsOfURL:
                        [NSURL URLWithString: @"http://www.site.com/json"]];

        NSError* error;

        noticias = [NSJSONSerialization JSONObjectWithData:data
                                                 options:kNilOptions
                                                   error:&error];

        dispatch_async(dispatch_get_main_queue(), ^{
            [self.tableView reloadData];
        });
    });
}

然后

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self fetchNoticias];
}

最后我遇到问题

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"NoticiasCell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

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

    NSArray *noticia = [noticias objectForKey:@"noticias"];
    NSDictionary *not = [noticias objectAtIndex:indexPath.row];
    NSString *firstTitle = [not objectForKey:@"titulo"];

    cell.textLabel.text = firstTitle;
    //cell.detailTextLabel.text = subtitulo;

    [cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];

    return cell;
}

问题在线：

NSArray *noticia = [noticias objectForKey:@"noticias"];

Answer 1

有几点意见：

您的JSON格式不正确，缺少逗号。它应该是：
```
{
    "noticias": [
                 {
                 "titulo":"teste"
                 },
                 {
                 "titulo":"teste 2"
                 }
                 ]
}
```
如果您没有添加丢失的逗号，则解析器会收到错误消息。例如，NSJSONSerialization将报告：

在字符109周围形成错误的数组

要阅读内容，您需要加载带有JSON内容的NSData，然后解析它，例如：

NSData *data = [NSData dataWithContentsOfFile:filename]; // or [NSData dataWithContentsOfURL:url];
NSError *error = nil;
NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];

if (error)
    NSLog(@"%@", error);
else
{
    NSArray *array = [dictionary objectForKey:@"noticias"];
    NSDictionary *item = [array objectAtIndex:indexPath.row];
    NSString *title = [item objectForKey:@"titulo"];

    NSLog(@"%@", firstTitle);
}

或者，使用新的，更简单的语法：

NSData *data = [NSData dataWithContentsOfFile:filename]; // or [NSData dataWithContentsOfURL:url];
NSError *error = nil;
NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];

if (error)
    NSLog(@"%@", error);
else
{
    NSArray *array = dictionary[@"noticias"];
    NSDictionary *item = array[indexPath.row];
    NSString *title = item[@"titulo"];

    NSLog(@"%@", title);
}

首先，为您班级的noticias中的@interface定义一个属性：

@property (nonatomic, strong) NSArray *noticias;

然后阅读noticias：

- (void)fetchNoticias
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData* data = [NSData dataWithContentsOfURL:
                        [NSURL URLWithString: @"http://www.site.com/json"]];

        NSError* error = nil;

        NSDictionary *results = [NSJSONSerialization JSONObjectWithData:data
                                                                options:kNilOptions
                                                                  error:&error];

        if (error) 
        {
            NSLog(@"%s: error=%@", __FUNCTION__, error);
            return;
        }

        self.noticias = [results objectForKey:@"noticias"];

        dispatch_async(dispatch_get_main_queue(), ^{
            [self.tableView reloadData];
        });
    });
}

然后

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self fetchNoticias];
}

，最后，cellForRowAtIndexPath：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"NoticiasCell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

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

    NSDictionary *noticia = [self.noticias objectAtIndex:indexPath.row];
    NSString *firstTitle = [noticia objectForKey:@"titulo"];

    cell.textLabel.text = firstTitle;
    //cell.detailTextLabel.text = subtitulo;

    [cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];

    return cell;
}

Answer 2

假设您的jsonData是“响应”

NSError* error;
NSDictionary* ResponseDic = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableLeaves error:&error];
NSArray* noticias = [ResponseDic objectForKey:@"noticias"];
NSDictionary* not = [noticias objectAtIndex:indexPath.row];

希望这对你有所帮助。

Answer 3

试试这个

      NSArray *array = [dictionary objectForKey:@"noticias"];
      for(int i=0;i<[array count];i++)
      {
       NSDictionary *item = [array objectAtIndex:i];
      NSString *title = [item objectForKey:@"titulo"];
       NSLog(@"%@",title);
      }

希望对你有所帮助。

xcode NSDictionary错误多阵列

3 个答案: