Create AutosizedCollectionView a convenient UICollectionView that makes dynamic sizing easier when using Auto Layout

Riot/Modules/Common/CollectionView/AutosizedCollectionView.swift

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+/*
+ Copyright 2019 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
+
+/// AutosizedCollectionView is a convenient UICollectionView that makes dynamic sizing easier when using Auto Layout
+class AutosizedCollectionView: UICollectionView {
+    
+    override var contentSize: CGSize {
+        didSet {
+            self.invalidateIntrinsicContentSize()
+        }
+    }
+    
+    override var intrinsicContentSize: CGSize {
+        return self.contentSize
+    }
+}