@StateObject & @ObservableObject
Apr 29, 2024
- Property wrapper to observe other classes, and have them updated in view
- Update current view when something gets updated in other classses.
1. Set up
a. Create a navigation Stack
b. custom data type
Now fruit model has string id, name and count
c. Create an array of fruit model
d. add data into List
inside the Hstatck text will bring the data from the fruitArray
e. onAppear function
f. onDelete
2. Create a custom class to hold extra data
a. Create a class outside of current View
- @Published works same as state.
b. import the class into a current View
c. bring the fruitArray function into the class
d. change the fruitArray → fruitViewModel.data or fruitViewModel.function
But, we can not still see the updated data in our view
e. Add @ObservedObejct on fruitViewModel & @ObservableObejct on FruitViewModel
f. Add isLoading
3. @StateObject
Why is important?
- Whenever the view get updated and reloaded, @ObservedObject also gets reloaded. When user wants to reload the page but data should be remained, @StateObject is persist.
→ @StateObject → INIT
→ @ObservedObejct → Subview
a. Create a Random Screen
b. Add a toolbar that link to Random Screen
C. delete onAppear and create a custom init() in FruitViewModel
d. Change the random screen to have array of fruitviewmodel
e. Add navigation link to have fruitviewmodel
Today, I learned about ObservableObject
and StateObject. These are property
wrappers that observe other classes
and update them in the view.
Whenever the view is updated and
reloaded, @ObservedObject also gets
reloaded. If you want to reload the
page but keep the data intact,
@StateObject is preferred.
You can use the custom dataset
from current view or in another view.
This way, you can update the dataset
and preserve the data when transitioning
to a different view with their data set.
#visionOS #AppleVisionPro #VisionPro #SpatialApp #SwiftUI #AppDevelopment
