Issue 155.  March 21st 2024

Comparing @Observable to ObservableObjects

In iOS 17, we’ve gained a new way to provide observable data to our SwiftUI views which is the @Observable macro.

We were using either an ObservableObject with @StateObject, @ObservedObject, or @EnvironmentObject whenever we had a reference type to observe in one of our SwiftUI views.

But with the new updates, the @Observable macro can only be applied to classes and we can observe their values with the @State or @Bindable property wrappers.

How it works:

The @Observable macro inserts a bunch of code when we compile our app and we can see the generated code with the Expand macro option by right-clicking on the macro in Xcode.

3 Ways to set up an @Observable observer to the SwiftUI views with 3 different property wrappers for 3 different purposes: @State: to cache the instance it’s applied to across view redraws. @Bindable: to create bindings to @Observable models @Environment: to add our @Observable objects to the environment where we don’t need to pass a specific key

Note:

@Observable allows users of an Observable to only be notified when a property that was accessed within something called withObservationTracking was changed.

Tips and Considerations for Using Lazy Containers in SwiftUI

This article explored some practical tips and important considerations aimed at enhancing developers’ ability to leverage SwiftUI’s lazy containers for improved app responsiveness and resource management.

Tips:

• Customize a data type that conforms to the RandomAccessCollection protocol for the incompatible data source to optimize performance and memory usage.
• Dynamically loading new data sets based on user scrolling or demand significantly enhances user experience, especially when dealing with large amounts of data.
• When we use the id Modifier on List's Lazy Loading Mechanism, it instantiates all the child views immediately even though they are not about to appear in the visible area.
• For structures with multi-layered subviews and rich states, the recommended practice is to elevate all relevant states to the top-level view, ensuring the correct maintenance of the state.
• In lazy containers, certain types of data do not immediately release the memory space they occupy unless they completely exit the lazy container view. By changing the state type, the eagerness for resource recycling can be improved.