IOS UIWebView get 404, 504 and other error problem solutions

UIWebView gets 404, 504 and other error codes

Problem description

When using webview, there is a problem:
If the access server returns an exception, such as errors such as 404 and 504, you need to display specific pictures and copywriting on the native side (the error codes of 404 and 504 are somewhat unsightly). Then, the question is, how can we know that the webview access is wrong, and what is wrong? ? ?

Problem analysis

After making a request from the webview, the one that can view the loading status of the webview is its proxy, so we start with the analysis from each proxy method.

 // The webview is called when it is instructed to load the content, and it will only be loaded if it returns YES.  - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType;
  // The webview has started to be called after loading a request  - (void)webViewDidStartLoad:(UIWebView *)webView;
  // Called after the webview ends the loading request  - (void)webViewDidFinishLoad:(UIWebView *)webView;
  // Called when an error occurs during request loading  - (void)webView:(UIWebView *)webView didFailLoadWithError:(nullable NSError *)error;

First of all, I must start with the didFailLoadWithError proxy method. I found that the method was not called when the request reached the 404 page. Why is this? It turns out that there was a problem with the loading process during this method, and we successfully got the 404 page, which is not considered a problem with the loading process.

Then, searching for the problem online, I found that the methods provided by netizens were all used to return the status code of NSHTTPURLResponse to make judgments. However, another warning appeared, sendSynchronousRequest was deprecated after iOS9, so the new method dataTaskWithRequest proxy was used.

 'sendSynchronousRequest:returningResponse:error:' is deprecated: first deprecated in iOS 9.0 - Use [NSURLSession dataTaskWithRequest:completionHandler:]

The above is the way to obtain the status code. In which proxy function is processed, we need to take a look at:

Through specific code analysis, it was found that the corresponding status code can be obtained by putting the shouldStartLoadWithRequest and webViewDid FinishLoad. The status code obtained by putting the webViewDidStartLoad is all 0. After analysis, it was found that when the webViewDidStartLoad method is called, the request request has been initiated and is waiting for the server to process the result.

Problem solving

In summary, there are two ways to deal with this problem in the end, namely sendSynchronousRequest and dataTaskWithRequest. The specific code is as follows:

 // Method 1  NSHTTPURLResponse *response = nil;
  [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];
  NSLog(@"statusCode:%ld", );
   // Method 2  NSURLSessionDataTask * dataTask = [[NSURLSession sharedSession] dataTaskWithRequest: completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    NSHTTPURLResponse *tmpresponse = (NSHTTPURLResponse*)response;
    NSLog(@"statusCode:%ld", );
  }];
  [dataTask resume];

The status code can be obtained in both the shouldStartLoadWithRequest and the webViewDidFinishLoad methods, and the specific status can be determined based on business needs.

Thank you for reading, I hope it can help you. Thank you for your support for this site!