CODEWITHSUNDEEP
iosobjective-cjsonuitableviewnsdictionary
Gangani Roshan
Gangani Roshan

Reputation: 583

How To Check key in key pair is available or not?

i am trying to learn json with iOS. i am trying to implement json data with UITableView. In my tableview row in Title and subtitle are displaying the values. I can load data in title but when try to load in subtitle, app is getting crashed because in subtitle result that field of json and in that many key-pair value is given. So It can't be possible to display in sub title in tableview.

My question is how can I load subtitle and if key in many key pair value is available to when click on that it gets redirected to other tableview for displaying that data.

My Code:

- (void)viewDidLoad {
    [super viewDidLoad];
    NSData *data=[NSData dataWithContentsOfURL:[NSURL URLWithString:@"https://query.yahooapis.com/v1/public/yql?q=select+*+from+weather.forecast+where+woeid%3D1100661&format=json"]];
    NSError *error=nil;
    id response=[NSJSONSerialization JSONObjectWithData:data options:
                 NSJSONReadingMutableContainers | NSJSONReadingMutableLeaves error:&error]; 
    if (error) {
        NSLog(@"%@",[error localizedDescription]);
    } else {
        _query = [response objectForKey:@"query"];
        NSLog(@"%@",_query);
        _keyArray = [_query allKeys];   
    }
}


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

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

    static NSString *cellIdentifier = @"cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];

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

    NSString *key = [_keyArray objectAtIndex:indexPath.row];
    //NSString *dictionary = [_query objectForKey:key];
    NSString *dictionary = [_query objectForKey:key];
    cell.textLabel.text = key;
    cell.detailTextLabel.text = dictionary;  
    return cell; 
}

Thanks.

Upvotes: 0

Views: 66

Answers (1)

Arun Kumar
Arun Kumar

Reputation: 798

Things I've understood from your question and comments, here is my answer step by step...

First I have taken a NSArray and a NSDictionary properties in my ViewController.h class like this.

{
NSArray *_allKeys;
}
 @property(nonatomic,strong) NSDictionary *query;

Then in ViewController.m I have created a setter method for query property , where I am setting the data into _query and _allKeys like this...

 -(void)setQuery:(NSDictionary *)query
{
    _query = query;
    _allKeys = [_query allKeys];
    if ([self isViewLoaded]) {
        [tableView reloadData];
    }

}

Now in UITableView datasource method cellForRow , I have updated your code..

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell" forIndexPath:indexPath];
    NSString *key = _allKeys[indexPath.row];
    id value = _query[key];
    cell.textLabel.text = key;
    if ([value isKindOfClass: [NSString class]]) {
        cell.accessoryType = UITableViewCellAccessoryNone;
        cell.detailTextLabel.text = (NSString*)value;
    }
    else if ([value isKindOfClass: [NSDictionary class]])
    {
        cell.detailTextLabel.text = @"More Info";
         cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    }
    else if ([value isKindOfClass: [NSArray class]])


       {
            cell.detailTextLabel.text = @"Multiple Entries Found";
             cell.accessoryType = UITableViewCellAccessoryNone;

// do something show array data with prototype custom cell
        }
        return cell;
    }

And now in UITableView delegate method didSelect , I have create a new instance for same ViewController (We can reuse it because , it has same UI layout), and passing the value of _query...

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *key = _allKeys[indexPath.row];
    id value = _query[key];
    if ([value isKindOfClass: [NSDictionary class]])
    {
        ViewController *nextVC = [self.storyboard instantiateViewControllerWithIdentifier:@"ViewController"];
        nextVC.query = value;
        [self.navigationController pushViewController:nextVC animated:YES];
    }
}

Note: I don't want to call that webservice call in ViewController.m , whenever I'm instantiating the ViewController instance . So I put the webservice code in AppDelegate didFinishLaunch method. 

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    NSData *data=[NSData dataWithContentsOfURL:[NSURL URLWithString:@"https://query.yahooapis.com/v1/public/yql?q=select+*+from+weather.forecast+where+woeid%3D1100661&format=json"]];
    NSError *error=nil;
    id response=[NSJSONSerialization JSONObjectWithData:data options:
                 NSJSONReadingMutableContainers | NSJSONReadingMutableLeaves error:&error];
    if (error) {
        NSLog(@"%@",[error localizedDescription]);
    } else {
     NSDictionary*   _query = [response objectForKey:@"query"];

        dispatch_async(dispatch_get_main_queue(), ^{
            ViewController *vc = (ViewController*)[(UINavigationController*)self.window.rootViewController topViewController];
            vc.query = _query;
        });
    }
    // Override point for customization after application launch.
    return YES;
}

It's up to you that where you put this code, but most preferably we should put following code in the previous UIViewController of your DatashowingViewController(Mine is ViewController) and pass the information to ViewController(like I have done), so that we can reuse the same UIViewController for showing same result.

I hope this answer will help you achieving your output.

Upvotes: 1

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