By the end of this lesson you can
- Apply iOS and Android platform conventions appropriately.
- Design for gestures, small screens and interrupted use.
- Handle offline states and notifications responsibly.
The idea
Mobile apps are used in short bursts, one-handed, on the move and often with poor connections. Good mobile design embraces these conditions.
Platform conventions
iOS (Apple's Human Interface Guidelines) and Android (Material Design) differ in navigation, controls, typography and system behaviours such as the back action. Follow each platform's conventions where users expect them, while keeping your brand and core flows consistent.
Touch and gestures
- Make touch targets at least around 44 to 48 points/pixels.
- Place frequent actions within thumb reach, often near the bottom.
- Always provide a visible alternative to hidden gestures such as swipe-to-delete.
Interrupted and offline use
Save progress automatically, restore state when people return and show clear offline states. Queue actions to sync later where possible, and tell people what happened.
Notifications and permissions
Ask for permissions (location, camera, notifications) in context, explaining the benefit, not on first launch. Send notifications only when they are timely and useful, and let people control them.
Why it matters in real projects
Mobile is the main or only device for many people. Ignoring platform conventions makes apps feel foreign; ignoring real-world conditions such as poor signal and interruptions makes them fail when people need them most. Respectful permissions and notifications protect trust and reduce uninstalls.
A realistic example
A parcel delivery app asks for location, camera and notification permissions on first launch; many people deny all three. The redesign asks for notifications only after someone books a delivery ("Get a message when your driver is nearby?"), and camera only when they choose to photograph a damaged parcel. Opt-in rates rise sharply, and the app saves photo uploads to send when signal returns.
Step by step
Review guidelines
Read the relevant parts of iOS and Android guidance.
Map contexts
List where, when and how people use the app.
Check touch
Review target sizes and thumb reach.
Add gesture alternatives
Provide visible controls for every gesture.
Design offline and resume
Design offline states, sync and state restoration.
Plan permissions
Ask in context with clear benefits.
Common mistakes
Mistake Asking for all permissions at launch.
Instead Ask in context when the benefit is clear.
Mistake Hidden gestures only.
Instead Provide visible alternatives.
Mistake Ignoring offline use.
Instead Design offline states and syncing.
Check your understanding
Choose an answer, then check it. There is an explanation either way.
Practice exercise
Exercise · about 45 min
Mobile audit
Audit a mobile app you use.
Steps
- Check targets, thumb reach and gestures.
- Turn on airplane mode and try a key task.
- Note how and when it asks for permissions.
- Propose three improvements.
Deliverable
An audit with three improvements.
Self-assessment
Tick each item when it is true of your exercise. Be honest; this is for you.
4 items
Summary
- Design for short, interrupted, one-handed use.
- Follow platform conventions.
- Handle offline states and save progress.
- Ask for permissions and send notifications respectfully.
Further reading
Third-party sources, chosen for reliability. They open in a new tab.
Your notes
Marking complete updates your course and roadmap progress.