ios - xcode NSDictionary 错误多数组

Question

我是 xcode 的新手，我需要帮助。

我有这个json:

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

我是怎么得到结果的？我试过

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

但我得到了一个错误，因为我有关键的“noticias”

更新:这是基于迄今为止收到的答案的尝试代码。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];
}

和我有问题的决赛

- (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;
}

在线问题:

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

Answer 1

几点观察:

您的 JSON 格式不正确，缺少逗号。它应该是:

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

如果你不添加缺少的逗号，你会从你的解析器中得到一个错误。例如，NSJSONSerialization将报告:

Badly formed array around character 109

要阅读内容，您需要加载 NSData使用 JSON 的内容，然后对其进行解析，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，为您的noticias 定义一个属性。在 @interface为您的类(class):

@property (nonatomic, strong) NSArray *noticias;

然后阅读您的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;
}