A SwiftUI Task modifier that gives you the current and previous ID values in the body

Task.swift

public extension View {
	func task<T: Equatable>(
		id: T,
		priority: TaskPriority = .userInitiated,
		@_inheritActorContext _ action: @Sendable @escaping (T, T) async -> Void
	) -> some View {
		self.modifier(TaskViewModifier(id: id, priority: priority, action: action))
	}
}

struct TaskViewModifier<T: Equatable>: ViewModifier {
	var id: T
	var priority: TaskPriority
	var action: @Sendable (T, T) async -> Void
	
	@State private var previousID: T?
	
	func body(content: Content) -> some View {
		content
			.task(id: id, priority: priority) {
				defer { previousID = id }
				await action(previousID ?? id, id)
			}
	}
}