Enable user mentions in Rich Text Editor

Riot/Modules/Pills/PillViewFlusher.swift

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+// 
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import UIKit
+import WysiwygComposer
+
+/// Defines behaviour for an object that is able to manage views created
+/// by a `NSTextAttachmentViewProvider`. This can be implemented
+/// by an `UITextView` that would keep track of views in order to
+/// (internally) clear them when required (e.g. when setting a new attributed text).
+///
+/// Note: It is necessary to clear views manually due to a bug in iOS. See `MXKMessageTextView`.
+@available(iOS 15.0, *)
+protocol PillViewFlusher: AnyObject {
+    /// Register a pill view that has been added through `NSTextAttachmentViewProvider`.
+    /// Should be called within the `loadView` function in order to clear the pills properly on text updates.
+    ///
+    /// - Parameter pillView: View to register.
+    func registerPillView(_ pillView: UIView)
+}
+
+@available(iOS 15.0, *)
+extension MXKMessageTextView: PillViewFlusher { }
+
+@available(iOS 15.0, *)
+extension WysiwygTextView: PillViewFlusher { }