I generally proceed like the following :
In windowDidLoad method, I write only these 3 lines :
NSURL *myURL = [[NSBundle mainBundle] URLForResource:@"help" withExtension:@"html"];
helpContent = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];
[self.myWebView loadHTMLString:helpContent
baseURL:[url URLByDeletingLastPathComponent]];