在通过Segue之前显示活动指示器

Question

Ok my First Controller is a UITabel and when a cell is passed it pushes to the Second View Controller. The Second Controller loads data from a webservice so the segue takes a little. I would like to show a SVProgressHUD when the cell is selected and then dismiss it after the data loaded but the SVProgressHUD instead shows after the Second View is loaded and only for aa couple milliseconds.I use this right now:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    [SVProgressHUD show];
    UITableViewCell *acell = [tableView cellForRowAtIndexPath:indexPath];
    [self performSegueWithIdentifier:@"pushCell" sender:acell];
}

Any way to show the SVProgressHUD immediately when cell is selected?

Answer 1

Apple recommends that when the user clicks on a tableViewCell the app should segue to the next view controller immediately. The fact that you feel you need to show a SVProgressHUD while the next view loads suggests to me that you are requesting the data using a synchronous method, which will block the main thread and make it appear that your app has frozen while it waits for the response.

The best practice for retrieving data is to always do so asynchronously (or on a background thread) so that your app always remains responsive. I would recommend changing your request to an asynchronous method (look into the NSURLRequest method initWithRequest:delegate: , for example). If you use that you can then show the SVProgressHUD in your second controller's viewDidLoad method, the transition to the second view controller will happen instantly when the user taps the table cell, and your app won't be locked up while the user waits for the data to download.

Here is more info about this method from the Apple Documentation