App crashes when I add a Activity indicator - iphone

Question

I'm writing an app and ind the app I got a Web View and I want to add an Activity Indicator. So I use this code:
timer = [NSTimer scheduledTimerWithTimeInterval:(1.0/2.0)
target:self selector:#selector(loadingPage) userInfo:nil repeats:YES];
But when I insert this code my app crashes and refers me to this code:
main.m
#import <UIKit/UIKit.h>
int main(int argc, char *argv[])
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
int retVal = UIApplicationMain(argc, argv, nil, nil);
[pool release];
return retVal;
}
at the line that starts with "int retVal..." it tells me "Thread 1: Program recieved signal: "SIGABRT"". By the way this code that it shows me is not something I wrote it was in the Xcode project from the beginning.
So my question is: Does anyone know a simple way of fixing this or another simple way of adding a Activity Indicator?
If someone knows a better way pleace write the code since I'm new to app development and still have allot to learn.
In advance thank you very much :)
Here's some more code:
.h file
#interface Ugeblad : UIViewController {
// Web View
IBOutlet UIWebView *faktaPDF;
// Activity Indicator View
IBOutlet UIActivityIndicatorView *pageLoadingIndicator;
NSTimer *timer;
}
#property (nonatomic, retain) IBOutlet UIWebView *faktaPDF;
#property (nonatomic, retain) IBOutlet UIActivityIndicatorView *pageLoadingIndicator;
#end
.m file
[faktaPDF addSubview:pageLoadingIndicator];
[faktaPDF loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:#"Website"]]];
timer = [NSTimer scheduledTimerWithTimeInterval:(1.0/2.0) target:self selector:#selector(loadingPage) userInfo:nil repeats:YES];

Answer 1

If by activity indicator you mean a spinning wheel (known as the UIActivityIndicatorView), you don't need a timer for it. It animates on its own; you just have to place it on the view and call [startAnimating].

Answer 2

Don't use an NSTimer for this, that's gross. Assign yourself as the delegate of the UIWebView and implement
-webViewDidStartLoad: to present your "loadingView" and then implement
-webView:didFinishLoad: and -webView:didFailLoadWithError: to hide your "loadingView".