Core data is framework that is used to manage model layer object in your application , Heap is store is stored dynamic memory and stack is stored in static memory . In heap is slow to access.Both memories are stored in ram. Heap memory is limted to size of virtual memory (ram), struct follows inhertiances properties and struct doesn't . Struct is value type . Class is reference type.escaping closure is a closure which is called after return in function.non escaping is called before return of the function .mvvm is desgin patter where view model is attached view and model is attached to viewmodel.viewmodel is dependency injection.hence viewmodel is bindling model and view