Question

I have a timer that I use to check a web address every 11 seconds. I use ASIHTTPRequest to set a delegate which reports the response form the web server. If I get the response I’m looking for, I want to update the UI. Unfortunately this doesn’t work, I suspect because I am not updating the UI from the UI thread.

Code to start and process timer:

- (void)startTimer {
BOOL timerStarted = false;
BOOL running = false;
BOOL readyToProcess = false;

if(!timerStarted){
    running = true;
    timerStarted = true;
    readyToProcess = true;
    autosaveTimer = [[NSTimer scheduledTimerWithTimeInterval:11
                                                      target:self
                                              selector:@selector(processWebCheckTimer:)
                                                    userInfo:nil
                                                     repeats:YES] retain];
}

}

- (void)processWebCheckTimer:(NSTimer*)theTimer {
    if ([VariableStore sharedInstance].success < 1) { //conversion not done, check again
        NSURL *url = [NSURL URLWithString:@"WEBSERVERURLHERE"];
        ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];
        [request setPostValue:oc_request forKey:@"queue"];
        [request setRequestMethod:@"POST"];
        [request setDelegate:self];
        [request startAsynchronous];
    }
}

Check response and update UI:

- (void)requestFinished:(ASIFormDataRequest *)request
{
    // Use when fetching text data
    NSString *responseString = [request responseString];
    if ([responseString rangeOfString:@"uccessfully converted"].location != NSNotFound) {
        [self performSelectorOnMainThread:@selector(threadStopAnimatingTwo:) withObject:nil waitUntilDone:YES]; //DOESNT WORK
        [autosaveTimer invalidate];

    }   

}

Function to Update UI:

- (void) threadStopAnimatingTwo:(id)data {
    NSLog(@"stop animating two");
    [loadingTwo stopAnimating];
    [labelTwo setTextColor:[UIColor lightGrayColor]];
}

Answer 1

It turns out that I was creating a new instance of my View controller when I didn’t need to. Because I created a new instance of the view controller, [self.loadingTwo] referred to a null UI component.