populate UITableView from json

I am trying to populate a UITableView with data from json result. I can get it to load from plist array no problem and I can even see my json. The problem I'm having is that the UITableView never gets to see the json results. please bear with me as this is my first time with Objective-C.

In my .h file

@interface TableViewViewController : UIViewController <UITableViewDataSource, UITableViewDelegate> {
    NSArray *exercises;
    NSMutableData *responseData;

}

In my .m file

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return  exercises.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView 
         cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    //create a cell
    UITableViewCell *cell = [[UITableViewCell alloc]
    initWithStyle:UITableViewCellStyleDefault
    reuseIdentifier:@"cell"];

    // fill it with contnets
    cell.textLabel.text = [exercises objectAtIndex:indexPath.row];
    // return it
    return cell;
}


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {       
    responseData = [[NSMutableData data] retain];
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://url_to_json"]];
    [[NSURLConnection alloc] initWithRequest:request delegate:self ];


    // load from plist
    //NSString *myfile = [[NSBundle mainBundle] pathForResource:@"exercise" ofType:@"plist"];
    //exercises = [[NSArray alloc] initWithContentsOfFile:myfile];
    [super viewDidLoad];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [responseData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [responseData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"Connection failed: %@", [error description]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [connection release];

    NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
    [responseData release];

 开发者_如何学Python   NSDictionary *dictionary = [responseString JSONValue];
    NSArray *response = [dictionary objectForKey:@"response"];

    exercises = [[NSArray alloc] initWithArray:response];
}

You need to tell your table view to reload. Try adding:

[tableView reloadData];

at the end of your -connectionDidFinishLoading method.

Use

[self.tableView reloadData];

You may need to add the following line of code at the end of your connectionDidFinishLoading method:

[self.tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO];

This will refresh the UITableView on the main thread since connectionDidFinishLoading is being performed on a different thread.