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forem / ForemWebView-ios

Forem core interface SDK
GNU General Public License v3.0
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Swipe gesture recognizer for goBack() anywhere in the view #15

Closed fdocr closed 3 years ago

fdocr commented 4 years ago

From where I see it this approach has two problems (A and B):

A) When swiping back from the edge we are using the native WKWebView feature exposed by allowsBackForwardNavigationGestures = true (here). The custom swipe gesture added in this PR doesn't peek the previous page as we swipe, instead it only refreshes back immediately.

Side by side comparison: https://share.getcloudapp.com/yAulplvK

After some initial research I don't think the WKWebView exposes an API to reproduce this behavior (simulate a "back Navigation" as if it were a native Navigation Controller popping a view). If this is not a problem we can stick with this for now, otherwise more research needs to be done in order to find a way to reproduce the better experience.

I was considering "relaying" the events from a PanGestureRecognizer that start anywhere on the screen, but editing the position of the taps to "simulate" an edge swipe. The intention is to try to "fool" the WKWebView implementation into thinking the swipe was actually coming from the edge, but I haven't had luck with this yet.

B) After a swipe back that takes the user to the previous page, my immediate reaction is to start scrolling up/down the main feed. The problem is that the swipe gesture refreshed the page and now the Javascript in the main feed triggers a refresh with any swipe up/down.

https://share.getcloudapp.com/7Ku878Q1

This doesn't happen in the DEV Community app when manually going back (calling webView.goBack()) which leads me to believe there's something that can be fixed here to avoid this. Nevertheless it feels like finally tackling forem/forem#7886 could fix this problem too

fdocr commented 4 years ago

From my research I've found that the _UIParallaxTransitionPanGestureRecognizer is the gesture recognizer responsible for the better transition, which in turn makes a call to _UINavigationInteractiveTransitionBase to handle the animation.

These are the Private APIs in question that we are technically not allowed to tap into.

benhalpern commented 3 years ago

I think we can close this for now. I don't think we're overly close to a solution here.

fdocr commented 3 years ago

I think we can close this for now. I don't think we're overly close to a solution here.

Closing for now, but the issue remains open and we can continue the conversation about possible solutions/enhancements there :)