Inspector

This is an exercise, a simulation of a scenario. This application is a simplification.

Application works with lists of dynamic objects with dynamic properties. Application allows user to inspect a selection of dynamic objects and edit properties of the selected objects.

WARNING: This application is BROKEN, It does not work as intended. Serves as a starter for a discussion.

This is a sample for a question at Apple Developer Forums.

Problem Definition

MODEL

• The Model consists of Dynamic Things.
• Dynamic Things have dynamic properties
• Properties are not known to the application developer (they can be created externally, by a user)

ENVIRONMENT

• The environment contains multiple dynamic collections of Things, we call them Filters
• The exact Filters are not known to the application developer

TOP LEVEL VIEW

• User can list Dynamic Things from a Filter
• There might be views of Dynamic Things that are described externally (not known to the app developer)

SELECTION AND INSPECTOR

• User can select one or multiple Dynamic Things in the list
• An Inspector displays properties of Things in the selection
• If multiple Things are selected, inspector displays values from properties that have only one distinct value, otherwise displays an empty value
• User can use Inspector to change some properteis of selected Things
• User can change properties of one or more Things at once using Inspector

View Hierarchy

 Window
   |
   +-- Content View (*>)
         |
         +-- Navigation View
         |     |
         |     +-- [sidebar] List of Thing Filters
         |     |
         |     +-- ThingListView(<*) – list of things, selectable, multiple
         |
         +-- Inspector(<*) – of selection in the above
 
 
 (*>) Selection – state, source of truth
 (<*) Selection - binding to


          Navigation         Inspector
 |<----------------------->|<--------->|

 +----------+--------------+-----------+
 | Filter 1 |**Thing 1*****| Selected: |
 | Filter 2 |  Thing 2     |  1,3      |
 | ....     |**Thing 3*****|           |
 |          | ...          | Name: ___ |
 +----------+--------------+-----------+
                 ^
                 |
                 +------- this can be 2D canvas, can be anything to present
                          a collection of selectable objects.
 
 
 Note: The ThingListView might as well be some kind of Canvas, or any other view,
       it does not have to be just a list view.

Known Issues

Issue #1: Binding set called on no change

Offending code location: Inspector.swift -> class Inspector -> var body -> nameBinding -> set

1. Pick a Filter (Thing collection)
2. Select multiple (more than one) items
3. One of (any):
   • Change selection to one item
   • Switch to another Filter

Result: All previously selected items will be changed.

Expected: No change happens.

What happened: set of a binding to a text filed is called on selection change.

File Description

• InspectorApp.swift - regular SwiftUI app with an environment object. Nothing special here.
• DynamicThing.swift - definition of core model objects.
• Environment.swift - definition of the model
• ContentView.swift - definition of an application content view – NavigationView with Inspector
• ThingListView.swift - List of Things - target for the NavigationView. Uses multiple selection.
• ThingView - view of a single thing in a list, simulating dynamic content/layout
• Inspector.swift - View of an inspector for Dynamic Things. Simulates editing of a dynamic variable of one or multiuple Things

Authors

• Stefan Urbanek [email protected]

License

• MIT