Question

I’m missing something about how UIActivityIndicatorView and NSTimer work together.

I’ve added this UIActivityIndicatorView in Interface Builder with the following settings:

The UIWebView is instantiated as self.webV and the UIActivityIndicatorView as self.indicator.

I have the following code in the implementation file:

-(void)viewDidLoad
{
    [super viewDidLoad];

    //Create UIWebView.
    if (!self.webV)
    {
        self.webV = [[UIWebView alloc] init];
}
    self.webV.delegate = self;

//Load web page.

    NSString *baseURLString = @"myURL.com";
    NSString *urlString = [baseURLString stringByAppendingPathComponent:@"myURL.com"];

    self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0/2.0 target:self selector:@selector(timerLoad) userInfo:nil repeats:YES];

    [self connectWithURL:urlString andBaseURLString:baseURLString];
}

-(void)timerLoad
{
    if (!self.webV.loading)
    {
        [self.indicator stopAnimating];
    }
    else
    {
        [self.indicator startAnimating];
    }
}

But when the UIWebView loads, no activity indicator shows up. What am I doing wrong or leaving out?

Thanks for the help, folks.

Answer 1

I’m really not sure on what the behaviour of the UIActivityIndicatorView is supposed to be if you repeatedly call start/stop on it. I am reasonably sure it isn’t meant to be used that way 🙂

So, even though your question is specific to NSTimer and UIActivityIndicatorView, it may be helpful to understand that you should approach your solution differently.

Instead of using a timer that repeatedly calls [self.indicator startAnimating] every half-second, you should use the webview delegate methods to toggle the UIActivityIndicatorView on and off.

       -(void)viewDidLoad
        {
            [super viewDidLoad];

            //Create UIWebView.
            if (!self.webV)
            {
                self.webV = [[UIWebView alloc] init];
            }
            self.webV.delegate = self;

        //Load web page.

            NSString *baseURLString = @"myURL.com";
            NSString *urlString = [baseURLString stringByAppendingPathComponent:@"myURL.com"];

            //self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0/2.0 target:self selector:@selector(timerLoad) userInfo:nil repeats:YES];

            [self connectWithURL:urlString andBaseURLString:baseURLString];
        }

- (void)webViewDidStartLoad:(UIWebView *)webView{
      //start animating
      [self.indicator startAnimating];
 }

- (void)webViewDidFinishLoad:(UIWebView *)webView{
         //stop animating
         [self.indicator stopAnimating];
    }