I have a custom UIWebView written like this :

.h

@interface MiniWebViewController : UIViewController {
    NSString* destinationURL;

    UIWebView* webView;
    UIActivityIndicatorView* activityIndicatorView;
}

@property (nonatomic, retain) NSString* destinationURL;

@property (nonatomic, retain) IBOutlet UIWebView* webView;
@property (nonatomic, retain) IBOutlet UIActivityIndicatorView* activityIndicatorView;

- (void) run;

@end

.m

@synthesize destinationURL;
@synthesize webView;
@synthesize activityIndicatorView;

- (id) initWithFrame:(CGRect)frame {
    if (self = [super initWithNibName:@"MiniWebView" bundle:nil]) {
        self.destinationURL = @"";

        self.view.frame = frame;
        self.activityIndicatorView.center = self.webView.center;
    }

    return self;
}

- (void) run {
    [self.webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:self.destinationURL]]];
}

It is called an initied from another ViewController :

- (void) aFunction {
    MiniWebViewController* oneViewController = [[MiniWebViewController alloc] initWithFrame:CGRectMake(/*Some Rect*/];
            oneViewController.webView.tag = i;
            oneViewController.destinationURL = /*SomeURL*/;
            oneViewController.webView.delegate = self;

            [self.view addSubview:oneViewController.view]; /* the Web view is inside this one */
            [oneViewController run];
    }

    - (void) webViewDidFinishLoad:(UIWebView *)webView {
        int webViewID = webView.tag;
        MiniWebViewController* webViewCon开发者_开发知识库troller = [self.webViews objectAtIndex:webViewID];
        [webViewController.activityIndicatorView stopAnimating];
    }

    - (void)webViewDidStartLoad:(UIWebView *)webView {
        int webViewID = webView.tag;
        MiniWebViewController* webViewController = [self.webViews objectAtIndex:webViewID];
        [webViewController.activityIndicatorView startAnimating];
    }

Into IB hidesWhenStopped is also checked. Everything is linked. The style of the indicator is set to "Large White" into IB.

When running, the indicator is not large, but small.

It is successfully started and stopped (delegate calls are triggered), but it doesn't hide when stopped.

What's the problem ? I don't see...

After a careful look in your code, you are modifying the UIActivityView in your init method. Change those so that they are in your viewDidLoad. At init, you view is not yet loaded, therefore, there is not an instance of those objects yet created in your controller.

These are the statement that need to be moved:

self.activityIndicatorView.hidesWhenStopped = YES;

self.view.frame = frame;
self.activityIndicatorView.center = self.webView.center;

This goes back to a fundamental of Objective-C: Sending a message to a nil object...returns nil. This is an annoying feature at times because there is no compile time warning, nor is there any runtime exception--a feature of the language.

Stupid I am, and XCode/cocoa really doesn't help.

I had loaded a wrong XIB name that DOES NOT exist. So I ask to load something that does not exist, and the app stil works, even showing and using objects that does not exist. Untill one call does not work as expected. No crash... It's nonsense.