Update to the SwiftUI API for the sake of NavigationLinks

[Richard-Gist]

While working on issue #101 to enable NavigationLinks, we discovered that the DSL we had decided on and implemented would not work. Fundamentally the API was broken in that our types were nested in the wrong direction. We were forced to correct this issue in PR #111 which now changes the API to nested closures instead of in-line calls.

For anyone currently consuming SwiftUI, you will have to make a couple of changes. Below is an example of what those differences are:

OLD VERSION

WorkflowLauncher(isLaunched: $workflowLaunched, startingArgs: "FR1 Input")
    .thenProceed(with: WorkflowItem(FR1.self)
                    .applyModifiers { $0.accentColor(.red) })
    .thenProceed(with: WorkflowItem(FR2.self)
                    .applyModifiers { fr2 in fr2.padding() })
    .thenProceed(with: WorkflowItem(FR3.self).persistence(.removedAfterProceeding))
    .onFinish { args in
        workflowLaunched = false
    }.onAbandon {
        print("workflowLaunched is set to false because abandon was called")
    }.background(Color.blue)

NEW VERSION

WorkflowLauncher(isLaunched: $workflowLaunched, startingArgs: "FR1 Input") {
    thenProceed(with: FR1.self) {
        thenProceed(with: FR2.self) {
            thenProceed(with: FR3.self).persistence(.removedAfterProceeding)
        }.applyModifiers { fr2 in fr2.padding() } // This applies to FR2
    }.applyModifiers { $0.accentColor(.red) } // This applies to FR1
}.onFinish { args in
    workflowLaunched = false
}.onAbandon {
    print("workflowLaunched is set to false because abandon was called")
}.background(Color.blue) // This applies to WorkflowLauncher

How to migrate?

While tedious, it is fairly straightforward on how to convert from the OLD version to the NEW version.

1. WorkflowLauncher now ends in a closure where you call thenProceed
2. thenProceed is now a function on View and so you remove the . from the call
3. thenProceed takes the FlowRepresentable type directly without the need for instantiating a WorkflowItem.
4. thenProceed can also take a closure for the next view in the chain, so you now nest your thenProceed calls.
5. applyModifiers and other methods you would attach to the WorkflowItem is now called off of thenProceed. That means at the end of thenProceed(with: FR1.self) or at the end of the closure on thenProceed.