Extract the HTML content from the existing UIWebview

Question

Extract the HTML content from the existing UIWebview

My UIWebview displays links that, when clicked, send JSON data. To show this data, I need to:

1) Detect when a link is clicked

2) Retrieve the JSON

To retrieve the JSON, I tried using

[webView stringByEvaluatingJavaScriptFromString:@"document.body.innerHTML"];

which resulted in:

<pre style="word-wrap: break-word; white-space: pre-wrap;">{some JSON}</pre>

Unfortunately,

[webView stringByEvaluatingJavaScriptFromString:@"document.getElementsByTagName(\"pre\")"];

returned an empty object. Are there any other methods to retrieve my JSON?

Regarding detecting when a link is clicked (question 1), is there a UIWebView delegate method available for this purpose?

javascript ios uiwebview

Answer 1

Answer №1

Encountered a similar issue and managed to resolve it using the following code snippet:

    NSString *jsonString = [webView stringByEvaluatingJavaScriptFromString:@"document.getElementsByTagName(\"pre\")[0].innerHTML"];

Answer 2

Encountered a similar issue and managed to resolve it using the following code snippet:

    NSString *jsonString = [webView stringByEvaluatingJavaScriptFromString:@"document.getElementsByTagName(\"pre\")[0].innerHTML"];

Answer 3

Answer №2

When it comes to iOS development, the iOS Developer Library is a valuable resource. It turns out that UIWebView offers a protocol that developers can subscribe to for delegate callbacks. If you're interested in learning more about these delegate callbacks, check this link out: http://developer.apple.com/library/ios/#documentation/uikit/reference/UIWebViewDelegate_Protocol/Reference/Reference.html#//apple_ref/occ/intf/UIWebViewDelegate

One of the important method from this protocol is:

    - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType

By implementing this protocol method, you can access the NSURLRequest object and extract information like the URL, allowing you to further customize your app's functionality.

Additionally, consider using the - (NSData *)HTTPBody instance method on NSURLRequest objects to retrieve JSON data. You can then utilize NSJSONSerialization from the Foundation framework to convert this data into NSObject instances. Here's a sample code snippet to get you started:

// UIWebView delegate method
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
  NSData *jsonData = request.HTTPBody;
  id jsonObj = [NSJSONSerialization JSONObjectWithData: jsonData options: NSJSONReadingMutableContainers error: nil];
  // perform actions with the retrieved object...
  
  return NO; // prevent the webview from loading the raw json data
  
}

Keep in mind that this code assumes pure JSON data. If there are HTML elements mixed in with the JSON, you may need to implement a mechanism to filter out the HTML content. For more detailed information on NSJSONSerialization, refer to the official documentation: http://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSJSONSerialization_Class/Reference/Reference.html

Happy coding!

Answer 4

When it comes to iOS development, the iOS Developer Library is a valuable resource. It turns out that UIWebView offers a protocol that developers can subscribe to for delegate callbacks. If you're interested in learning more about these delegate callbacks, check this link out: http://developer.apple.com/library/ios/#documentation/uikit/reference/UIWebViewDelegate_Protocol/Reference/Reference.html#//apple_ref/occ/intf/UIWebViewDelegate

One of the important method from this protocol is:

    - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType

By implementing this protocol method, you can access the NSURLRequest object and extract information like the URL, allowing you to further customize your app's functionality.

Additionally, consider using the - (NSData *)HTTPBody instance method on NSURLRequest objects to retrieve JSON data. You can then utilize NSJSONSerialization from the Foundation framework to convert this data into NSObject instances. Here's a sample code snippet to get you started:

// UIWebView delegate method
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
  NSData *jsonData = request.HTTPBody;
  id jsonObj = [NSJSONSerialization JSONObjectWithData: jsonData options: NSJSONReadingMutableContainers error: nil];
  // perform actions with the retrieved object...
  
  return NO; // prevent the webview from loading the raw json data
  
}

Keep in mind that this code assumes pure JSON data. If there are HTML elements mixed in with the JSON, you may need to implement a mechanism to filter out the HTML content. For more detailed information on NSJSONSerialization, refer to the official documentation: http://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSJSONSerialization_Class/Reference/Reference.html

Happy coding!

Extract the HTML content from the existing UIWebview

Answer №1

Answer №2

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