title: Prevent Realm from overwriting a property when updating an Object
body: <p>I've setup a REST API to realm object in iOS. However I've found an issue with creating a favorite flag in my object. I've created a favorite bool, however everytime the object is updated from the API it sets the favorite to default false again. Here I want this flag to not be updated, since the favorite only is stored locally. How can I achieve this?</p>
  
  <pre><code>class Pet: Object{
      dynamic var id: Int = 1
      dynamic var title: String = ""
      dynamic var type: String = ""
      dynamic var favorite: Bool = false
  
  
      override class func primaryKey() -&gt; String {
          return "id"
      }
  }
  </code></pre>
  
  <p><strong>CreateOrUpdate</strong></p>
  
  <pre><code>let pet = Pet()
  pet.id = 2
  pet.name = "Dog"
  pet.type = "German Shephard"
  
  
  try! realm.write {
      realm.add(pet, update: true)
  }
  </code></pre>