webview实现缓存

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:WHITE_BOARD] cachePolicy:theApp.mbCache?NSURLRequestReturnCacheDataElseLoad:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:60];
        
       [request addValue:@"1001" forHTTPHeaderField:@"qav"];
        [request addValue:UserBearer forHTTPHeaderField:@"Authorization"];
        
        [mpWebView loadRequest:request];