Not understanding how UIActivityIndicatorView works with NSTimer - objective-c

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];
}

Answer 2

There could be several reasons. It could load so fast that the loading is already done, or it never loaded at all because something is wrong with the URL.
This isn't the cause of your problem, but you never invalidate your timer, which you should.
I was also going to make the point that you should use delegate methods instead of a timer, but pdriegen beat me to it.