https://developer.apple.com/videos/play/wwdc2019/226/

프레젠테이션 슬라이드

Principles of Data Flow

[PlayerView] ---- [true]

Source of Truth

• Property Wrapper
  Wraps property Access with additional Behavior

• @Binding Property Wrapper
  Read and write without ownership
  Derivable from @State

Anatomy of an Update

class PodcastPlayserStore: BindableObject {
	var didChange = PassthroughSubject<Void, Never>()
    //...
    func advance() {
    	currentEpisode = nextEpisode
        currentTime = 0.0
        // Notofy subscribers that the palyer changed
        didChange.send()
    }
}

BindableObject?

struct MyView: View {
	@ObjectBinding var model: MyModelObject
    ...
}

MyView(model: modelInstance)

Environment

Data applicable to an entire hierarchy
Convenience for indirection
Accent color, right-to-left, and more

Understanding Your Data

---

• @State
  View - local
  Value
  Framework Managed

• Bindable Object
  External
  Reference
  Developer Managed

• @Binding
  First class reference to data
  Great for reusability
  Use $ to derive from source

---

Using State Effectively

Limit use if possible
Use derived Binding or value
Prefer Bindable Object for persistence
Example: Button highlighting