ios - How to load data from JSON url in UITableView? - iphone

Question

I'm new to iPhone development,I'm trying to bind data from JSON Url in UITableview, but I'm getting an error in the below code.
- (void)viewDidLoad
{
SBJsonParser *parser = [[SBJsonParser alloc] init];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://80f237c226fa45aaa09a5f5c82339d46.cloudapp.net/DownloadService.svc/Courses"]];
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
statuses = [parser objectWithString:json_string error:nil];
[self.dropdownTblView reloadData];
for (NSDictionary *status in statuses)
{
_altTitle = [status valueForKey:#"Title"];
NSLog(#"Title %#",_altTitle);
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSLog(#"%d",[statuses count]);
return [statuses 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] autorelease];
}
return cell;
//Here I'm getting an error
id obj = [statuses objectAtIndex:indexPath.row];
NSString *name = [obj valueForKey:#"Title"];
cell.textLabel.text =name;
return cell;
}
This is my JSON
[
{
"Id": 1,
"Title": "Tamil to English",
"AltTitle": "த|மி|ழ்| |மூ|ல|ம்| |ஆ|ங்|கி|ல|ம்",
"Description": "Learn English through Tamil",
"Code": 1,
"Version": "1.0",
"SourceLanguageIndicator": "அ",
"TargetLanguageIndicator": "A",
"SourceLanguageCode": "ta",
"TargetLanguageCode": "en",
"Updated": "2013-02-21T03:33:19.6601651+00:00"
}
]
Any ideas? Thanks in advance.

Answer 1

You're returning the cell twice in the same scope, try to delete the first return cell;, also you're calling reloadData on the table just before the for loop; in this case probably the dataSource of the table is still empty, so call reloadData just after the for loop.
EDIT:
It's strange what is happening, the objectFromString must return a NSArray or a NSDictionary but it seems that is pointing to an NSSet. I can suggest 2 things in addition:
It seems that you're not usig ARC since you're calling autorelease on the UITableViewCell. In this case you're leaking parser and json_string in the viewDidLoad, so release them.
Make sure to call [super viewDidLoad]; (you're not doing this in your code).

Answer 2

Maybe because you set the type of obj as id. It is too generic and may not know how to respond to valueForKey. Have you tried declaring obj as an NSDictionary * instead? Like the code below:
NSDictionary *obj = [statuses objectAtIndex:indexPath.row];
NSString *name = [obj valueForKey:#"Title"];

Answer 3

Use the Below code in your ViewDidload and Run the Project , it will work.
Note :You're returning the cell twice, try to delete the first return
cell;
- (void)viewDidLoad
{
[super viewDidLoad];
statuses=[[NSMutableArray alloc]init];
NSURL *myURL = [NSURL URLWithString:#"http://80f237c226fa45aaa09a5f5c82339d46.cloudapp.net/DownloadService.svc/Courses"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:myURL cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
NSLog(#"Finished with status code: %i", [(NSHTTPURLResponse *)response statusCode]);
id jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:nil];
NSLog(#"jsonObject=%#",jsonObject);
statuses=[jsonObject mutableCopy];
[self.coursetable reloadData];
}];
NSLog(#"myURL=%#",myURL);
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSLog(#"%d",[statuses count]);
return [statuses 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] ;
}
id obj = [statuses objectAtIndex:indexPath.row];
cell.textLabel.text =[obj valueForKey:#"Title"];
return cell;
}

Answer 4

Yes I was thinking right, statuses is not NSArray, it is NSSet so if you call objectAtIndex on NSSet it will crash.To get array convert NSSet into NSArray.
NSArray *array =[statuses allObjects];

Answer 5

- (void)viewDidLoad
{
NSString *dictStr=#"{\"Id\": 1,\"Title\": \"Tamil to English\",\"AltTitle\": \"த|மி|ழ்| |மூ|ல|ம்| |ஆ|ங்|கி|ல|ம்\",\"Description\": \"Learn English through Tamil\",\"Code\": 1,\"Version\": \"1.0\",\"SourceLanguageIndicator\": \"அ\",\"TargetLanguageIndicator\": \"A\",\"SourceLanguageCode\": \"ta\",\"TargetLanguageCode\": \"en\",\"Updated\": \"2013-02-21T03:33:19.6601651+00:00\"}";
NSDictionary *rootDict =[NSJSONSerialization JSONObjectWithData: [dictStr dataUsingEncoding:NSUTF8StringEncoding]
options: NSJSONReadingMutableContainers
error: nil];
NSArray *keys=[[rootDict allKeys] sortedArrayUsingSelector:#selector(compare:)];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [keys count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier=#"cellIdentifier";
UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell==nil) {
cell=[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
cell.textLabel.text=[rootDict valueForKey:[keys objectAtIndex:indexPath.row]];
return cell;
}
remember rootDict and keys will be declared as global.