What's the difference between @Bindable and @Binding?
What's the difference between @Bindable and @Binding? 관련
Updated for Xcode 15
SwiftUI provides two properties wrappers that use very similar names to provide wildly different functionality. No, I don't know why, either. However, I can at least explain to you what the difference is, so you're sure to always use the correct options.
The @Binding property wrapper is designed to let us read and write some external piece of data – something that was created elsewhere, such as an @State property from a parent view. If you were to create a custom text editor view, for example, you'd want to use @Binding to store access to the data you're writing, so that whichever parent view uses your text editor can say, “here is where you should store the user's text.”
In contrast, the @Bindable property wrapper allows us to get bindings from any property in an @Observable object, including all SwiftData model objects. If you create a local @Observable object using @State, you'll automatically be given bindings by the @State property wrapper. However, if you've been passed an object without any bindings – an object you know is @Observable – then you can use @Bindable to create bindings for you.
If the distinction still seems fuzzy to you, think about the older @ObservedObject property wrapper from SwiftUI. If you made a view that had some kind of object as a property you wouldn't be able to make bindings to it, but if you marked it with @ObservedObject then you would get bindings.
The only real difference is that @Bindable is sometimes needed inside your view body, perhaps because you want to make the whole object bindable, or because you're inside a List or a ForEach loop and need to make individual items bindable.
If you can, it's preferable to use @Bindable directly on your property, like this:
@Bindable var user: User
However, that isn't possible in some situations, such as when you've used @Environment already. For times like that, use @Bindable directly in your view body, like this:
@Bindable var user = user