NSJSONSerialization Json嵌套子

Question

我正在尝试深入到嵌套的JSon数组中，我已经成功地完成了上面的级别，但我无法弄清楚如何更深入。

我需要记录图像@url，我已经附加了一个屏幕显示，以显示我需要它去的地方。

谢谢:)

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- (void)viewDidLoad
{
    [super viewDidLoad];


    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

    NSURL *url = [NSURL URLWithString:@"http://api.storageroomapp.com/accounts/511a4f810f66026b640007b8/collections/511a51580f66023bff000ce9/entries.json?auth_token=Zty6nKsFyqpy7Yp5DP1L&preview_api=1"];

    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [[NSURLConnection alloc] initWithRequest:request delegate:self];


}

-(void)connectionDidFinishLoading:(NSURLConnection *) connection{
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

    NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:nil error:nil];

    NSDictionary *arrayDictionary = dictionary[@"array"];

    news = arrayDictionary[@"resources"];

    [tableView reloadData];
}





-(void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
    UIAlertView *errorView = [[UIAlertView alloc] initWithTitle:@"Error" message:@"The data could not be downloaded - please make sure you're connected to either 3G or Wi-FI" delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil];
    [errorView show];
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}


-(int)numberOfSectionsInTableView:(UITableView *)tableView{
    return  1;
}


-(int)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    return [news count];
}



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

    NSDictionary *newsItem = news[[indexPath row]];


    NSString *title = newsItem[@"title"];
    NSString *date = newsItem[@"date"];
    NSString *thumb = newsItem[@"tablethumb"];




    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MainCell"];

    if (cell == nil) {
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"MainCell"];

        [[cell textLabel] setText:title];
        [[cell detailTextLabel] setText:date];





        if((NSNull *)thumb == [NSNull null]){
            NSLog(@"no image");
        } else{
            NSLog(@ "image = %@", thumb);

        }


    }
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    return cell;
}

Answer 1

对于遍历嵌套对象，您可以使用valueForKeyPath方法并使用点语法向下钻取层次结构。

下面这样的代码将从您的newsItem字典中获取url值：

NSDictionary *newsItem = news[[indexPath row]];
NSString *thumbUrl = [newsItem valueForKeyPath:@"tablethumb.url"];

PS。如果你真的用@作为属性的前缀，那么从@ is a special token used as an operator开始使用valueForKeyPath可能会遇到麻烦。在这种情况下，您可以这样做：

NSDictionary *newsItem = news[[indexPath row]];
id tablethumb = [newsItem objectForKey:@"tablethumb"];
NSString *thumbUrl = @"";
// Check if not null and access the @url
if (tablethumb != [NSNull null])
  thumbUrl = tablethumb[@"@url"];

Answer 2

尝试像这样从字典中访问值，

NSLog(@"URL: %@",[newsItem objectForKey:@"@url"]);