add ModelContainerPreview conecept, move SampleData, fix Exercise, ExerciseUnit, ExerciseType

WorkoutsPlus/Features/Exercise/AddExercise.swift

@@ -17,8 +17,8 @@ struct AddExercise: View {
 		
 		@State private var name: String = ""
 		@State private var description: String = ""
-		@State private var type = ExerciseType("")
-		@State private var unit = ExerciseUnit("", symbol: "")
+		@State private var type: ExerciseType?
+		@State private var unit: ExerciseUnit?
 		
 		@State private var isPartOfProgression: Bool = false
 		
@@ -41,12 +41,14 @@ struct AddExercise: View {
 																																		• Sprint → Time or Distance
 																																		""")) {
 												Picker("Exercise Type", selection: $type) {
+														Text("None").tag(nil as ExerciseType?)
 														ForEach(exerciseTypes, id: \.self) { type in
 																Text("\(type.name)").tag(type as ExerciseType?)
 														}
 												}
 												.pickerStyle(NavigationLinkPickerStyle())
 												Picker("Exercise Unit", selection: $unit) {
+														Text("None").tag(nil as ExerciseUnit?)
 														ForEach(exerciseUnits, id: \.self) { unit in
 																Text("\(unit.name) (\(unit.symbol))").tag(unit as ExerciseUnit?)
 														}
@@ -66,7 +68,7 @@ struct AddExercise: View {
 										ToolbarItem(placement: .confirmationAction) {
 												Button("Save") {
 														withAnimation {
-																save()
+																saveNew()
 																dismiss()
 														}
 												}
@@ -76,7 +78,7 @@ struct AddExercise: View {
 				}
 		}
 		
-		private func save() {
+		private func saveNew() {
 				let exerciseToSave = Exercise(name)
 				modelContext.insert(exerciseToSave)