Dealing with various extension data types

extensions.m

NSExtensionItem *item = self.extensionContext.inputItems.firstObject;
NSItemProvider *itemProvider = item.attachments.firstObject;

// Shared plain text is stored here. Content varies wildly based on app.
NSString *sharedPlainText = [item.attributedContentText string];

if ([itemProvider hasItemConformingToTypeIdentifier:(NSString *)kUTTypePropertyList]) {
    [itemProvider loadItemForTypeIdentifier:(NSString *)kUTTypePropertyList
                                    options:nil
                          completionHandler:^(NSDictionary *item, NSError *error) {
                              // If it's a "webpage". This type seems to be mostly shared by Safari.
                              // We can run custom JS if it's a webpage, so get more info that way
                              // e.g. page title, currently selected text, etc.
                              NSDictionary *results = [item objectForKey:NSExtensionJavaScriptPreprocessingResultsKey];
                              // Probably don't need sharedPlainText here since we can get
                              // lots of info from the page itself
                          }];
} else if ([itemProvider hasItemConformingToTypeIdentifier:(NSString *)kUTTypeURL]) {
    [itemProvider loadItemForTypeIdentifier:(NSString *)kUTTypeURL options:nil completionHandler:^(NSURL *url, NSError *error) {
      // Maybe it's just a URL
      // May want to use sharedPlainText as well, maybe as the title
    }];
} else if (sharedPlainText)  {    
    // Or maybe it's plain text only
    // Could use an NSDataDetector to get a URL out of it, if possible
} else {
    // Or maybe there's nothing at all <flanders.gif>
    // Not sure why this would happen, might be a beta bug. 
    // I managed to get it when sharing the calendar event from apple.com/live :/
}

To get info from a "webPage" type, it seems like you really need a JS preprocessor file. You can set this in your extension's Info.plist with the key NSExtensionJavaScriptPreprocessingFile inside the NSExtensionAttributes dictionary. See https://gist.github.com/blork/e2780fd7e2a1a95f57d3 for an example.