ObservableObject

ObservableObject is a protocol in the Swift programming language, primarily used within the SwiftUI framework, designed to facilitate data binding and dependency management. It allows objects to be observed for changes, enabling other parts of an application to react automatically when their state is modified.

To implement ObservableObject, a class must conform to the protocol and be marked with the @objcMembers attribute if it needs to be accessed from Objective-C code. Within the class, properties that should trigger updates when changed must be declared with the @Published property wrapper. When a property marked with @Published is modified, ObservableObject automatically publishes a change notification.

This mechanism is fundamental to SwiftUI's declarative UI paradigm. Views in SwiftUI can subscribe to changes in an ObservableObject by using property wrappers like @StateObject or @ObservedObject. @StateObject is used to create and own an instance of an ObservableObject, ensuring it persists for the lifetime of the view. @ObservedObject, on the other hand, is used when a view receives an ObservableObject instance from another source, such as a parent view or an environment object.

When a published property of an ObservableObject changes, any view observing it will be re-rendered to reflect the updated data. This ensures that the UI remains consistent with the underlying data model without requiring manual updates or explicit observer registration in most cases. ObservableObject simplifies the management of shared mutable state across different parts of an application, promoting a more reactive and maintainable codebase.