在iOS中解析嵌套对象

Question

I'm parsing objects from my Rails app to my iOS app using JSON. I want to be able to show a thumbnail for each one of my posts, but the images are nested inside an array, and not only that I have many images for each post and each image has a thumb and a full image. How can I show the thumb of the FIRST image for each of my posts?

Thanks.

JSON

upcoming_releases: [
{
  id: 2,
  release_name: "Lebron X Low",
  release_price: "165",
  release_colorway: "Raspberry-Red/Blueprint-Court",
  release_date: "2013-09-07T00:00:00.000Z",
  url: "http://obscure-lake-7450.herokuapp.com/upcoming/2",
  images: [
    {
      image_file: {
        image_file: {
          url: "https://s3.amazonaws.com/soleresource/uploads/releases/nike-lebron-x-low-raspberry.jpg",
          thumb: {
            url: "https://s3.amazonaws.com/soleresource/uploads/releases/thumb_nike-lebron-x-low-raspberry.jpg"
        }
      }
    }
   },
   {
     image_file: {
       image_file: {
         url: "https://s3.amazonaws.com/soleresource/uploads/releases/nike-lebron-x-low-raspberry.jpg-2",
         thumb: {
           url: "https://s3.amazonaws.com/soleresource/uploads/releases/thumb_nike-lebron-x-low-raspberry-2.jpg"
          }
        }
      }
    },
  {
]

},

My view controller

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSURL *upcomingReleaseURL = [NSURL URLWithString:@"http://obscure-lake-7450.herokuapp.com/upcoming.json"];

    NSData *jsonData = [NSData dataWithContentsOfURL:upcomingReleaseURL];

    NSError *error = nil;

    NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];

    self.upcomingReleases = [NSMutableArray array];

    NSArray *upcomingReleasesArray = [dataDictionary objectForKey:@"upcoming_releases"];

    for (NSDictionary *upcomingReleaseDictionary in upcomingReleasesArray) {
        UpcomingRelease *upcomingRelease = [UpcomingRelease upcomingReleaseWithName:[upcomingReleaseDictionary objectForKey:@"release_name"]];
        upcomingRelease.release_price = [upcomingReleaseDictionary objectForKey:@"release_price"];
        upcomingRelease.release_colorway = [upcomingReleaseDictionary objectForKey:@"release_colorway"];
        upcomingRelease.release_date = [upcomingReleaseDictionary objectForKey:@"release_date"];
        upcomingRelease.url = [upcomingReleaseDictionary valueForKeyPath:@"url"];
        [self.upcomingReleases addObject:upcomingRelease];
    }

}


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

    UpcomingRelease *upcomingRelease = [self.upcomingReleases objectAtIndex:indexPath.row];

    if ( [upcomingRelease.url isKindOfClass:[NSString class]]) {
        NSData *imageData = [NSData dataWithContentsOfURL:upcomingRelease.thumbURL];
        UIImage *image = [UIImage imageWithData:imageData];
        cell.imageView.image = image;
    }
    else {
//        cell.imageView.image = [UIImage imageNamed:@"cover.png"];
    }

    cell.textLabel.text = upcomingRelease.release_name;
    cell.detailTextLabel.text = [NSString stringWithFormat:@"$%@", upcomingRelease.release_price];

    return cell;
}

UpcomingRelease.h

@property (nonatomic, strong) NSString *url;

- (NSURL *) thumbURL;

Answer 1

How are you generating that JSON? It's not valid, the key strings aren't quoted which is probably OK but the array elements aren't separated which I can't imagine parses at all. I'd suggest using the JSON gem if you're not:

require 'json'

...

JSON.generate({:key => "value"}) # Use your actual object of course

The structure seems a little wacky beyond that, with an image_file key nested inside an image_file key, I'd rename the outer key to something more descriptive if you have that ability.

The array should read in fine and just be a nested NSArray:

UpcomingRelease.h :

@property (nonatomic, strong) NSArray *url;

Your ViewController :

upcomingRelease.release_date = [upcomingReleaseDictionary objectForKey:@"release_date"];
upcomingRelease.url = [upcomingReleaseDictionary valueForKeyPath:@"url"];
upcomingRelease.images = [upcomingReleaseDictionary objectForKey:@"images"];

[self.upcomingReleases addObject:upcomingRelease];

...

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

UpcomingRelease *upcomingRelease = [self.upcomingReleases objectAtIndex:indexPath.row];
NSString *thumbURLString = nil;

if ([upcomingRelease.images isKindOfClass:[NSArray class]] && [upcomingRelease.images count])
    thumbURLString = [[[[[upcomingRelease.images objectAtIndex:0] objectForKey:@"image_file"] objectForKey:@"image_file"] objectForKey:@"thumb"] objectForKey:@"url"];

if (thumbURL)
{
    NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:thumbURLString]];
    UIImage *image = [UIImage imageWithData:imageData];
    cell.imageView.image = image;
}
else {
//  cell.imageView.image = [UIImage imageNamed:@"cover.png"];
}

Answer 2

The images entry in your upcoming_releases dictionary appears to be an array of dictionaries with 1 item in each dictionary ( image_file ) which is a dictionary. However, I would note that your sample JSON for the images entry is malformed in a couple ways:

-there is no closing ] in the array
-there are no commas between the dictionary
-there are 3 opening brackets and 1 closing bracket

Assuming that is a typo and you fix it...

To store the image info in your model you would do the following:

for (NSDictionary *upcomingReleaseDictionary in upcomingReleasesArray) {
    UpcomingRelease *upcomingRelease = [UpcomingRelease upcomingReleaseWithName:[upcomingReleaseDictionary objectForKey:@"release_name"]];
    upcomingRelease.release_price = [upcomingReleaseDictionary objectForKey:@"release_price"];
    upcomingRelease.release_colorway = [upcomingReleaseDictionary objectForKey:@"release_colorway"];
    upcomingRelease.release_date = [upcomingReleaseDictionary objectForKey:@"release_date"];
    upcomingRelease.url = [upcomingReleaseDictionary valueForKeyPath:@"url"];
    //note images property should be NSArray
    upcomingRelease.images = [upcomingReleaseDictionary objectForKey:@"images"];
    [self.upcomingReleases addObject:upcomingRelease];
}

To show the thumb of the first image:

NSDictionary *imageFileDictionary = [upcomingRelease.images objectAtIndex:0];
NSDictionary *imageInfoDictionary = [imageFileDictionary objectForKey@"image_file"];
NSString *thumb = [imageInfoDictionary objectForKey@"thumb"];