JSON Data in Table View iOS loaded - ios

Question

I can parse data and see the output also but I am not able to display them in table view
when I call the view that contain JSON the application is crashed
This is my code:
In the first line of code we define a macro that gives us back a background queue – I like having a kBgQueue shortcut for that, so I can keep my code tighter.
In the second line of code we create a macro named kLatestKivaLoansURL which returns us an NSURL pointing to this URL http://api.kivaws.org/v1/loans/search.json?status=fundraising.
#define kBgQueue dispatch_get_global_queue(
DISPATCH_QUEUE_PRIORITY_DEFAULT, 0) //1
#define kLatestKivaLoansURL [NSURL URLWithString:
#"http://api.kivaws.org/v1/loans/search.json?status=fundraising"] //2
#interface TeacherViewController ()
#end
#implementation TeacherViewController
- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
// Custom initialization
}
return self;
}
Defined kBGQueue as a macro which gives us a background queue?
- (void)viewDidLoad
{
[super viewDidLoad];
dispatch_async(kBgQueue, ^{
NSData* data = [NSData dataWithContentsOfURL:kLatestKivaLoansURL];
[self performSelectorOnMainThread:#selector(fetchedData:)
withObject:data waitUntilDone:YES];
});
}
#synthesize latestLoans;
#synthesize arrayOfFighterName;
Will be called and the NSData instance will be passed to it. In our case the JSON file is relatively small so we’re going to do the parsing inside fetchedData: on the main thread. If you’re parsing large JSON feeds (which is often the case), be sure to do that in the background.
- (void)fetchedData:(NSData *)responseData {
//parse out the json data
NSError* error;
NSDictionary* json = [NSJSONSerialization
JSONObjectWithData:responseData //1
options:kNilOptions
error:&error];
latestLoans = [json objectForKey:#"loans"]; //2
arrayOfFighterName=[[NSMutableArray alloc] init];
//NSLog(#"loans: %#", latestLoans); //3
for( int i = 0; i<[latestLoans count]; i++){
// NSLog(#"%#", [matchListArray objectAtIndex:i]);
arrayOfFighterName[i]=[[latestLoans objectAtIndex:i] objectForKey:#"name"];
// NSLog(#"%#", [arrayOfFighterName objectAtIndex:i]);
}
}
- (void)viewDidUnload
{
[super viewDidUnload];
latestLoans = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
#warning Potentially incomplete method implementation.
// Return the number of sections.
return 1;
}
Displaying the result in table view
but unfortunately the result does not display and the app is crashed
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
#warning Incomplete method implementation.
// Return the number of rows in the section.
return [arrayOfFighterName count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView
dequeueReusableCellWithIdentifier:#"TeacherCell"];
cell.textLabel.text = [arrayOfFighterName objectAtIndex:indexPath.row];
return cell;
// NSLog(#"viewDidLoad is called");
}
/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
// Return NO if you do not want the specified item to be editable.
return YES;
}
*/
/*
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the row from the data source
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}
*/
/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
}
*/
/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
// Return NO if you do not want the item to be re-orderable.
return YES;
}
*/
#pragma mark - Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// Navigation logic may go here. Create and push another view controller.
/*
<#DetailViewController#> *detailViewController = [[<#DetailViewController#> alloc] initWithNibName:#"<#Nib name#>" bundle:nil];
// ...
// Pass the selected object to the new view controller.
[self.navigationController pushViewController:detailViewController animated:YES];
*/
}
#end

Answer 1

Change the fetched data method like:
- (void)fetchedData:(NSData *)responseData {
//parse out the json data
NSError* error;
NSDictionary* json = [NSJSONSerialization
JSONObjectWithData:responseData //1
options:kNilOptions
error:&error];
latestLoans = [json objectForKey:#"loans"]; //2
arrayOfFighterName=[[NSMutableArray alloc] init];
//NSLog(#"loans: %#", latestLoans); //3
for( int i = 0; i<[latestLoans count]; i++){
// NSLog(#"%#", [matchListArray objectAtIndex:i]);
arrayOfFighterName[i]=[[latestLoans objectAtIndex:i] objectForKey:#"name"];
// NSLog(#"%#", [arrayOfFighterName objectAtIndex:i]);
}
[tableView reloadData];
}
Because the at the first time, the tableView is loaded before the data is added to the array. Due to the asynchronous call. The data is parsed and added to array when the data is retrieved from the server. So you need to reload your tableView to display the data.
Please refer about the asynchronous call in this tutorial.