[flutter_appauth] add cancellation method for as web authentication session

[kodejack]

As this repository hosts two packages, please ensure the PR title starts with the name of the package that it relates to using square brackets (e.g. [flutter_appauth])
#643

[MaikuB]

Thanks for the PR. Can you add some details to your original post on what this PR solves. Currently I'm taking a guess from the API docs for the new method. I would be keen to see if you're able to share info on how to reproduce the problem and/or a recording. Is the example app impacted by the problem this that PR solves? If so, can the example app be updated to show how it makes use of the addition as well?

[vkammerer]

We would be keen to see this PR merged as our application needs it.

Our use case is that we need to close the ASWebAuthenticationSession view from the flutter application before it has completed.

[MaikuB]

@vkammerer any chance you show a video and/or demo code using what this PR provides? I didn't get what you mean by your explanation. My understanding is this is about closing the browser and that's normally handled as part of the redirect so wondering if I'm missing/misunderstanding something

[vkammerer]

@MaikuB our use case is that we want to close the ASWebAuthenticationSession before it redirects normally. To be more precise, the flow is as follows:

• we open an ASWebAuthenticationSession
• the user is taken through a web flow that can sometimes finish by tapping an app link / universal link in the browser, or sometimes lead to opening these app links / universal links from third party applications
• in both cases, the flutter app will handle these links while the ASWebAuthenticationSession is still open
• then we want to close the ASWebAuthenticationSession and present our Flutter implementation of the flow's completion.

[MaikuB]

Thanks @vkammerer for the info. At which point does the cancellation method get called and how does it get called? This was one of the reasons I wanted to see if the example app can be updated to show the usage. On that note, does the example app fit the criteria for using the method? So far I can tell the method can close the modal browser by making minor tweaks (e.g. don't await the call that initiates the await request and call the cancellation method after some delay). However, a redirection typically closes the browser so I'm wondering what I'm missing.

Note I'm aware it won't hurt to the method but trying to get more understanding, seeing if it's something suits being in the example app and if there are some examples of usages that I could add through API docs and/or the readme

Edit: is there something that makes this unique to iOS/macOS as well?

Sorry I forgot/missed that @kodejack linked this PR to #643

[MaikuB]

So sorry about confusion @kodejack. The original post still kept the PR message template that is meant to be replaced that I missed you had linked to the issue number underneath it to describe about the problem in more depth. Functionality-wise PR is fine but would you be able to look into the following

• rename the method. The use of the word "session" refers to ASWebAuthenticationSession but this ends up causing a clash with the notion of a session that refers to a session after a user has logged in. I would recommend something like dismissExternalUserAgent as it's close to the name used within the AppAuth iOS SDK and the notion of an external user agent already exists in this plugin. The documentation would end needing adjustment as a result
• The API docs for the method within the AppAuth iOS SDK takes a boolean parameter to indicate if the dismissal will be animated or note. Would you be able to expose a similar boolean parameter?

[MaikuB]

Was there a reason to pass an empty HashMap<>()? I believe passing null would suffice

[MaikuB]

Similar to my comment on Android side, from what I've seen and tried, calling result(nil) would have sufficed