在看切克闹项目，有个加载网页的：
#pragma mark --
#pragma mark UIWebViewDelegate
- (void)webViewDidStartLoad:(UIWebView *)webView
{
[UIApplication
sharedApplication].networkActivityIndicatorVisible =
YES;
}
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
[UIApplication
sharedApplication].networkActivityIndicatorVisible =
NO;
}
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
{
[UIApplication
sharedApplication].networkActivityIndicatorVisible =
NO;
}