'SwiftUI Previews w/Mock Realm

I am running into a problem trying to use an in memory realm configuration with previews. When the preview executes it returns an error. The diagnostics gives the following error:

MessageError: Connection interrupted

I have the following class defined to mock the realm data.

class MockRealms {
   static var previewRealm: Realm {
      get {
         var realm: Realm
         let identifier = "previewRealm"
         let config = Realm.Configuration(inMemoryIdentifier: identifier)
         do {
            realm = try Realm(configuration: config)
            try realm.write {
               for category in Categories.allCases {
                  _ = Category(name: category.rawValue)
               }
            }
            try realm.write {
               _ = Settings(type: .fixed, int: 3.375, dp: 25.0, term: 30)
            }
            return realm
         } catch let error {
            fatalError("Error: \(error.localizedDescription)")
         }
      }
   }
}

In the view we are using the @ObservedResults to get the categories from the Realm.

struct PropertyListView: View {
   @ObservedResults(Category.self) var categories
   @Binding var showInfo: Bool
   @Binding var showInfoButton: Bool
   @Binding var showGuide: Bool
   @Binding var showGuideButtton: Bool

   var body: some View {
      NavigationView {
         ScrollView {
            VStack {
               ForEach(categories) { category in
                  PropertyCategoryView(category: category)
               }
            }
         }
      }
      .navigationBarTitle("Property List")
      .navigationBarBackButtonHidden(false)
   }
   .navigationViewStyle(.stack)
}

The preview section is as follows:

struct PropertyListView_Previews: PreviewProvider {
   static var previews: some View {
      Group {
         PropertyListView(showInfo: .constant(false), showInfoButton:
            .constant(true), showGuide: .constant(false), showGuideButton:
            .constant(false))
            .environment(\.realm, MockRealms.previewRealm)
         PropertyListView(showInfo: .constant(false), showInfoButton:
            .constant(true), showGuide: .constant(false), showGuideButton:
            .constant(false))
            .environment(\.realm, MockRealms.previewRealm)
            .preferredColorScheme(.dark)
      }
   }
}

Any help would be most appreciated.

swiftuimockingrealmswiftui-previewsrealm-ios


Solution 1:[1]

On the main content view I call the PropertyListView with an environment setting realmConfiguration and pass that into the PropertyListView. So I changed the PreviewProvider to pass simply the in-memory Realm configuration and then everything seems to work just fine.

struct PropertyListView_Previews: PreviewProvider {
   static var previews: some View {
      Group {
         PropertyListView(showInfo: .constant(false), showInfoButton:
           .constant(true), showGuide: .constant(false), showGuideButton:
           .constant(false))
           .environment(\.realmConfiguration, Realm.Configuration(inMemoryIdentifier: "previewRealm", schemaVersion: 1))
        PropertyListView(showInfo: .constant(false), showInfoButton:
           .constant(true), showGuide: .constant(false), showGuideButton:
           .constant(false))
           .environment(\.realmConfiguration, Realm.Configuration(inMemoryIdentifier: "previewRealm", schemaVersion: 1))
           .preferredColorScheme(.dark)
     }
  }

}

With Realm changing almost every other day it is like walking on quicksand. It is a wonderful DB for mobile development because they are constantly making it better, but boy you really have to stay on top of the changes.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Cosmtar

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