One Big Mistake in SwiftUI Growth: Letting Views Own Business Logic

The Hidden Cost of Fast UI Iteration

When SwiftUI apps grow quickly, developers often place business decisions directly in views. It works early, then release velocity collapses because every small UI tweak risks behavior regression.

Step 1: Separate rendering state from domain actions

struct LessonScreenState {
    var title: String
    var progressText: String
    var isNextEnabled: Bool
}

protocol LessonActions {
    func tapNext()
    func tapReplayAudio()
}

Step 2: Keep decision rules in a reducer/service layer

struct LessonReducer {
    mutating func reduce(_ event: Event, state: inout LessonScreenState) {
        switch event {
        case .answerCorrect:
            state.progressText = "Great. Move to the next challenge."
            state.isNextEnabled = true
        case .answerWrong:
            state.progressText = "Try again with a slower pace."
            state.isNextEnabled = false
        }
    }
}

Step 3: Snapshot-test view states

Treat each state as a screenshot-worthy contract, so you can refactor layout safely.

Pitfalls

• View structs calling network/data layers directly.
• Side effects triggered from random button handlers.
• No state fixtures for regression tests.

Verification

• All critical screens can render from fixture state.
• Business rules are testable without UI runtime.
• UI refactors do not alter domain behavior.