iOS SDK (Swift) / Rendering flows

Rendering flows

One view. It fetches the flow by key, caches it, renders every screen as SwiftUI, and calls you back with the answers.

The view

OnboardingScreen.swift

import SwiftUI
import UpliftFunnel

struct OnboardingScreen: View {
    var body: some View {
        UpliftFunnelFlowView(flowKey: "welcome") { result in
            print(result.endReason)   // "completed" / "abandoned" / "skipped"
            print(result.variables)   // every answer the user gave
            print(result.source)      // network / cache / revalidated
        }
    }
}

Parameter	Type	Default	Description
flowKey	String	—	The flow's slug, from the dashboard.
onCompleted	((UpliftFunnelFlowResult) -> Void)?	nil	Called once, when the flow ends for any reason.
userVariables	[String: JSONValue]?	nil	Values your app already knows, seeded into the session before the first screen.
forceRefresh	Bool	false	Skip the cache and refetch. Normal starts are cache-first.
loadingView	(() -> AnyView)?	nil	Replaces the default spinner.
errorView	((Error, @escaping () -> Void) -> AnyView)?	nil	Replaces the default error state. The closure's second argument retries the fetch.

What comes back

Field	Type	Description
endReason	String	Why it ended: "completed", "abandoned", "skipped", or a custom reason the flow authored.
variables	[String: JSONValue]	Every answer collected over the session.
source	FetchSource	network, cache, or revalidated — useful for surfacing offline state.
experiment	UpliftFunnelExperimentAssignment?	The A/B assignment this session ran under, or nil.

Seeding what you already know

A flow should not ask for a name your app has. Pass it in, and the screens can interpolate it and branch on it from the first frame.

swift

UpliftFunnelFlowView(
    flowKey: "welcome",
    onCompleted: { result in save(result.variables) },
    // Anything your app already knows. Available to the flow as
    // {{first_name}} and to its transition conditions.
    userVariables: [
        "first_name": .string(user.firstName),
        "is_subscriber": .bool(user.isSubscriber)
    ]
)

Your own loading and error states

The defaults are a spinner and a message with a Retry button. Replace either when the flow is the first thing a user sees and the default would look like a different app.

swift

UpliftFunnelFlowView(
    flowKey: "welcome",
    onCompleted: handle,
    loadingView: { AnyView(MySplash()) },
    errorView: { error, retry in
        AnyView(MyErrorView(message: error.localizedDescription, retry: retry))
    }
)

Running an experiment

Same view, routed through the experiments endpoint: the SDK attaches a sticky subject id, the server buckets the user into a stable variant, and the assignment comes back on the result.

swift

UpliftFunnelFlowView.experiment("paywall-copy-test") { result in
    // Typed assignment — nil for a flow with no running experiment.
    let variant = result.experiment
    analytics.log("onboarding_done", [
        "experiment_id": variant?.experimentId,
        "variant_id": variant?.variantId,
        "variant_name": variant?.variantName
    ])
}

Safe to leave in production after a decision — a stopped experiment serves the baseline and a rolled-out one serves the winner. More on experiments →

Starting a session yourself

When you want the fetch to happen before the view exists — during a splash, say — start it directly and render the session later.

swift

// Start it early — on app launch, behind your splash — and render later.
let start = try await UpliftFunnel.start("welcome", userVariables: seed)

print(start.source)        // where the JSON came from
print(start.flowVersion)   // the published version that was rendered
print(start.experiment)    // assignment, if any

// Then render the session you already have.
UpliftFunnelSessionView(session: start.session) { variables, reason in
    save(variables)
}

UpliftFunnel.startExperiment(_:) is the experiment equivalent and returns the same FlowSessionStart.