I have a URL string which contains "#".For example,

NSString* urlStr = @"https://developer.apple.com/library/ios/#/legacy/library/documentation/Xcode/Conceptual/ios_development_workflow/10-Configuring_Development_and_Distribution_Assets/identities_and_devices.html#//apple_ref/doc/uid/TP40007959-CH4-SW";
urlStr = [urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSURL* url = [NSURL URLWithString:urlStr];
[[self.webViewSample mainFrame] loadRequest:[NSURLRequest requestWithURL:url]];

After using encoding ,the "#" is replaced by "%23".If you don't use encoding, the NSURL will be nil. My problem is that the webview load incorrect webpage which is different from Browser.How can I handle this url string so that I can load the correct webpage?

So I think from your question now, the root problem is that Apple's documentation uses some rather oddly formed URLs. They contain more than one # character, which isn't technically valid for a URL. The first is valid (and important); any others should be escaped.

Safari is able to handle this, I think because it does more than just display/use the raw URL string. The best solution I've found to date is to hand off to WebView's pasteboard handling, like so:

- (NSURL *)URLFromString:(NSString *)string;
{
    static NSPasteboard *pboard;
    if (!pboard) pboard = [[NSPasteboard pasteboardWithUniqueName] retain];

    [pboard clearContents];
    [pboard writeObjects:@[string]];

    NSURL *result = [WebView URLFromPasteboard:pboard];
    return result;
}

More details at http://www.mikeabdullah.net/webkit-encode-unescaped-urls.html