added nameForReuse check

refactored buttons to either create or set

Signed-off-by: Matt Bruce <matt.bruce@verizon.com>

MVMCoreUI/Atomic/Atoms/Buttons/ButtonGroup.swift

@@ -18,6 +18,7 @@ import VDS
     open var viewModel: ButtonGroupModel!
     open var delegateObject: MVMCoreUIDelegateObject?
     open var additionalData: [AnyHashable : Any]?
+    open var previousModel: ButtonGroupModel?
     
     //--------------------------------------------------
     // MARK: - MoleculeViewProtocol
@@ -31,25 +32,45 @@ import VDS
         return PillButton.estimatedHeight(with: buttonModel, delegateObject)
     }
     
-    public func viewModelDidUpdate() {
+    public func viewModelDidUpdate() {                
-        var buttonBases = [ButtonBase]()
-        viewModel.buttons.forEach { buttonModel in
-            if let buttonBaseType = try? ModelRegistry.getHandler(buttonModel) as? MoleculeViewProtocol.Type,
-               let button = buttonBaseType.init(model: buttonModel, delegateObject, additionalData) as? VDS.ButtonBase {
-                buttonBases.append(button)
-            }
-        }
         surface = viewModel.surface
         isEnabled = viewModel.enabled
         alignment = viewModel.alignment
         rowQuantityPhone = viewModel.rowQuantityPhone
         rowQuantityTablet = viewModel.rowQuantityTablet
+        
         if let childWidthValue = viewModel.childWidthValue {
             childWidth = .value(childWidthValue)
         } else if let childWidthPercentage = viewModel.childWidthPercentage {
             childWidth = .percentage(childWidthPercentage)
         }
-        buttons = buttonBases
+        
+        // create / set the moleculeViews
+        if (previousModel == nil) || Self.nameForReuse(with: previousModel!, delegateObject) != Self.nameForReuse(with: viewModel, delegateObject) {
+            var buttonBases = [ButtonBase]()
+            viewModel.buttons.forEach { buttonModel in                
+                do {
+                    let buttonBaseType = try ModelRegistry.getHandler(buttonModel) as! MoleculeViewProtocol.Type
+                    let button = buttonBaseType.init(model: buttonModel, delegateObject, additionalData) as! VDS.ButtonBase
+                    buttonBases.append(button)
+                } catch {
+                    if let errorObject = MVMCoreErrorObject.createErrorObject(for: error, location: #function) {
+                        MVMCoreLoggingHandler.shared()?.addError(toLog: errorObject)
+                    }
+                }
+            }
+            buttons = buttonBases
+            
+        } else {
+            // only set the molecule views
+            for (index, buttonBase) in buttons.enumerated() {
+                if let button = buttonBase as? MoleculeViewProtocol, index < viewModel.buttons.count {
+                    button.set(with: viewModel.buttons[index], delegateObject, additionalData)
+                }
+            }
+            // force redraw
+            setNeedsUpdate()
+        }
     }
     
     //--------------------------------------------------
@@ -66,4 +87,22 @@ import VDS
     public func updateView(_ size: CGFloat) {
         setNeedsUpdate()
     }
+    
+    public static func nameForReuse(with model: MoleculeModelProtocol, _ delegateObject: MVMCoreUIDelegateObject?) -> String? {
+        // This will aggregate names of molecules to make an id.
+        guard let model = model as? ButtonGroupModel else {
+            return "buttonGroup<>"
+        }
+        var name = "buttonGroup<"
+        for case let item in model.buttons {
+            if let moleculeClass = ModelRegistry.getMoleculeClass(item),
+                let nameForReuse = moleculeClass.nameForReuse(with: item, delegateObject) {
+                name.append(nameForReuse + ",")
+            } else {
+                name.append(item.moleculeName + ",")
+            }
+        }
+        name.append(">")
+        return name
+    }
 }