Create SizingViewHeightStore to store a view height relative to a width.

Riot/Modules/Room/Views/BubbleCells/SizableCell/SizingViewHeight.swift

@@ -0,0 +1,47 @@
+/*
+ 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 Foundation
+
+final class SizingViewHeight: Hashable, Equatable, CustomStringConvertible {
+    
+    // MARK: - Properties
+    
+    let uniqueIdentifier: Int
+    var heights: [CGFloat /* width */: CGFloat /* height */] = [:]
+    
+    var description: String {
+        return "<\(type(of: self))> uniqueIdentifier: \(uniqueIdentifier) - heights: \(heights)"
+    }
+    
+    // MARK: - Setup
+    
+    init(uniqueIdentifier: Int) {
+        self.uniqueIdentifier = uniqueIdentifier
+    }
+    
+    // MARK: - Hashable
+    
+    func hash(into hasher: inout Hasher) {
+        hasher.combine(self.uniqueIdentifier)
+    }
+    
+    // MARK: - Equatable
+    
+    static func == (lhs: SizingViewHeight, rhs: SizingViewHeight) -> Bool {
+        return lhs.uniqueIdentifier == rhs.uniqueIdentifier
+    }
+}