Facebook authentication in a UIWebView does not redirect back to original page on my site asking for auth

Question

In our iOS app, we have a UIWebView that shows web content on our domain that has a Facebook comment module. The comment module requires that the user is signed in with facebook. When user clicks on the sign in button, they are taken through the sign in flow, but are never redirect back to our page. They end up on an FB owned page that just tells the user "You are now signed in".

Repro steps:

1. Create a UIWebView in an iOS app, and host a Facebook comment module on a page hosted on some domain you own (e.g. http://foo.com/test.htm).
2. Click on the Sign In button on the comment module and notice you are redirect to FB sign in.
3. Sign in with valid FB credentials and observe what happens.

After you sign in (step 3) I would expect that after a successful authentication, you are redirected back to the original page (e.g http://foo.com/test.htm) so you can continue your interaction. However, this isn't happening.

Instead, you are on an FB owned page that just says something like "You are now signed in" and you are trapped there. No redirect happens.

Is this indeed a bug or is there something else I should be doing to ensure the redirect happens?

Answer 1

If you are just supporting iOS 8 and up, you can use WKWebView which already implements the functionality described by @kabuko:

// Container view including the main WKWebView
var container : UIView?
var popupWebView : WKWebView?

override func viewDidLoad() {
    super.viewDidLoad()

    let prefs = WKPreferences()
    prefs.javaScriptEnabled = true
    // allow facebook to open the login popup
    prefs.javaScriptCanOpenWindowsAutomatically = true

    let config = WKWebViewConfiguration()
    config.preferences = prefs

    webView = WKWebView(frame: container.frame, configuration: config)
    webView?.UIDelegate = self
    webView?.navigationDelegate = self
}

// callback if the content of the webView wants to create a new window
func webView(webView: WKWebView, createWebViewWithConfiguration configuration: WKWebViewConfiguration, forNavigationAction navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? {
    // create new popup webview and add it to the view hierarchy
    popupWebView = WKWebView(frame: container.frame, configuration: configuration)
    container.addSubview(popupWebView!)
    return popupWebView
}

func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
    // if the main webView loads a new page (e.g. due to succesful facebook login)
    // remove the popup
    if (popupWebView != nil) {
        popupWebView?.removeFromSuperview()
        popupWebView = nil
    }
}