UX: remove iPad keyboard user setting from iOS 13

Removes setting for iOS devices that support Visual Viewport API.

On devices where it was previously enabled, it was causing some scrolling drift when invoking the composer.

app/assets/javascripts/discourse/components/composer-body.js.es6

@@ -7,6 +7,7 @@ import afterTransition from "discourse/lib/after-transition";
 import positioningWorkaround from "discourse/lib/safari-hacks";
 import { headerHeight } from "discourse/components/site-header";
 import KeyEnterEscape from "discourse/mixins/key-enter-escape";
+import { iOSWithVisualViewport } from "discourse/lib/utilities";
 
 const START_EVENTS = "touchstart mousedown";
 const DRAG_EVENTS = "touchmove mousemove";
@@ -132,16 +133,12 @@ export default Ember.Component.extend(KeyEnterEscape, {
       $document.on(END_EVENTS, endDrag);
     });
 
-    if (this.shouldUseVisualViewportListener()) {
+    if (iOSWithVisualViewport()) {
       this.viewportResize();
       window.visualViewport.addEventListener("resize", this.viewportResize);
     }
   },
 
-  shouldUseVisualViewportListener() {
-    return this.capabilities.isIOS && window.visualViewport !== undefined;
-  },
-
   viewportResize() {
     const composerVH = window.visualViewport.height * 0.01;
 
@@ -178,7 +175,7 @@ export default Ember.Component.extend(KeyEnterEscape, {
   willDestroyElement() {
     this._super(...arguments);
     this.appEvents.off("composer:resize", this, this.resize);
-    if (this.shouldUseVisualViewportListener()) {
+    if (iOSWithVisualViewport()) {
       window.visualViewport.removeEventListener("resize", this.viewportResize);
     }
   },

app/assets/javascripts/discourse/controllers/preferences/interface.js.es6

@@ -10,7 +10,11 @@ import {
   setLocalTheme
 } from "discourse/lib/theme-selector";
 import { popupAjaxError } from "discourse/lib/ajax-error";
-import { safariHacksDisabled, isiPad } from "discourse/lib/utilities";
+import {
+  safariHacksDisabled,
+  isiPad,
+  iOSWithVisualViewport
+} from "discourse/lib/utilities";
 
 const USER_HOMES = {
   1: "latest",
@@ -51,7 +55,9 @@ export default Ember.Controller.extend(PreferencesTabController, {
 
   @computed()
   isiPad() {
-    return isiPad();
+    // TODO: remove this preference checkbox when iOS adoption > 90%
+    // (currently only applies to iOS 12 and below)
+    return isiPad() && !iOSWithVisualViewport();
   },
 
   @computed()

app/assets/javascripts/discourse/lib/safari-hacks.js.es6

@@ -1,5 +1,8 @@
 import debounce from "discourse/lib/debounce";
-import { safariHacksDisabled } from "discourse/lib/utilities";
+import {
+  safariHacksDisabled,
+  iOSWithVisualViewport
+} from "discourse/lib/utilities";
 
 // TODO: remove calcHeight once iOS 13 adoption > 90%
 // In iOS 13 and up we use visualViewport API to calculate height
@@ -95,7 +98,7 @@ function positioningWorkaround($fixedElement) {
       fixedElement.style.position = "";
       fixedElement.style.top = "";
 
-      if (window.visualViewport === undefined) {
+      if (!iOSWithVisualViewport()) {
         fixedElement.style.height = oldHeight;
         Ember.run.later(
           () => $(fixedElement).removeClass("no-transition"),
@@ -176,7 +179,7 @@ function positioningWorkaround($fixedElement) {
 
     fixedElement.style.top = "0px";
 
-    if (window.visualViewport === undefined) {
+    if (!iOSWithVisualViewport()) {
       const height = calcHeight();
       fixedElement.style.height = height + "px";
       $(fixedElement).addClass("no-transition");

app/assets/javascripts/discourse/lib/utilities.js.es6

@@ -544,6 +544,10 @@ export function isAppleDevice() {
 
 let iPadDetected = undefined;
 
+export function iOSWithVisualViewport() {
+  return isAppleDevice() && window.visualViewport !== undefined;
+}
+
 export function isiPad() {
   if (iPadDetected === undefined) {
     iPadDetected =
@@ -554,6 +558,8 @@ export function isiPad() {
 }
 
 export function safariHacksDisabled() {
+  if (iOSWithVisualViewport()) return false;
+
   let pref = localStorage.getItem("safari-hacks-disabled");
   let result = false;
   if (pref !== null) {