Mobile app projects become much easier when students understand state. State is the information the app remembers while the user interacts with it: selected tab, current score, saved preferences, form entries, or loaded data.
Scenario: habit tracker app
A student builds a habit tracker. The app has a list of habits, a selected habit, and a streak count. If the streak resets when the user rotates the phone or leaves the screen, the problem may be lifecycle-related.
Common state questions
- Where is the current value stored?
- When does the screen reload?
- Does the app need temporary state or persistent storage?
- Which event handler updates the value?
Debugging approach
Students should trace one user action at a time. For example: tap button, handler runs, state updates, screen re-renders, value appears. If one step does not happen, the bug is easier to isolate.
More complex example
If the app loads habit data from an API, it should also handle loading, success, and error states. A blank screen is not a helpful error message. A good app tells the user whether data is still loading or whether something failed.
Practice prompt
Design the state variables for a simple quiz app: current question, selected answer, score, timer, and whether results are visible. Then describe which user action changes each variable.