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SwiftUI state management interview questions
State management is the heart of SwiftUI, so it is the most reliable area to be tested on. The key is ownership and the single source of truth.
The property wrappers and their roles
@State owns simple value-type state local to a view; @Binding passes a mutable reference to that state down to a child; @StateObject creates and owns a reference-type model for a view's lifetime, while @ObservedObject receives one it does not own; @Environment reads shared values injected from above. With Observation, @State holds @Observable models and @Bindable provides bindings.
Answering about ownership
Interviewers want you to reason about who owns each piece of state and who is allowed to mutate it, avoiding duplicate sources of truth that drift out of sync. Explain lifting state up when siblings must share it, passing bindings down for editable values, and using the Environment for cross-cutting dependencies rather than threading them through every initializer.
Go deeper than a summary
Share Your Screen works topics like this through in full: 75 solved Swift problems with tests, 9 real case studies, and 7 annotated mock interviews, so you rehearse the live round instead of just reading about it.
Frequently asked
@StateObject or @ObservedObject?
Use @StateObject where the view creates and owns the model so it survives view updates; use @ObservedObject when the model is created elsewhere and passed in.
What is the single source of truth in SwiftUI?
Each piece of state should have exactly one owner. Other views read it via bindings or the environment rather than keeping their own copy that can drift.