I really wish this had been built in to iOS in the same way.
The activity stack works across applications, which means a back gesture always brings you back to the screen before it, even when several applications work together on a task.
I wasn't even aware it was supposed to be a button
But it will not appear if the app opens the webpage as its own View (instead of opening Safari). In that case, there is no button and the user has to hunt for how to go back. And the user has no way of knowing whether an app will open Safari or will open the webpage itself.
iOS requires users to build muscle memory in learning how to use each app. Android requires users to maintain a back stack in their head to remember what came before. Switching between the two is very jarring.
If it's a card webview, just swipe it down from the top edge.
> Switching between the two is very jarring.
I think that's the crux of the problem. Someone who's used to one style and has built muscle memory and some kind of hierarchy and ontology of the interaction with the system will have trouble with a different paradigm. That doesn't necessarily mean there's something wrong with either - they're just different, and some people will prefer one over the other.
Switching between GNOME and KDE, or vice-versa, has a similar effect.
Would be consistent.
> It appears every time [long list of qualifications]
Is inconsistent.
OTOH if the current app was opened manually by the user, it won't be there.
It just feels so “out of space” and tacked on.
An example of an intent is "can anyone open this PDF file" or "the user wants to pick a file, can any app do that and let me know what they picked?"-- those file pickers could also be from your network browser app, or Dropbox, etc.
And since activities are serializable (well, technically the intents that led to those activities being started), Android can do this without requiring the apps deep in the app stack to be running. It can freeze those apps to reserve resources and restart them at the specific activity when the user returns, if necessary.
iOS does have limited inter-app linking (it's the tiny little back arrow and the previous app name that you'll sometimes see at the very top of the screen), but since back gestures aren't universal, the only reliable way to activate that feature is to tap it, since the app may not even understand back gestures, let alone do the extra work of relinquishing control when their own local back stack is empty.