How do I add turn-by-turn directions to a mobile app?

To add turn-by-turn directions to a mobile app, you typically combine a map SDK, a routing/directions service, and navigation UI/logic.

1) Pick a maps provider

Common options:

• Google Maps Platform
• Mapbox
• HERE
• TomTom
• Apple Maps / MapKit (iOS-specific)

Most providers offer:

• Map display
• Directions API
• Route polyline rendering
• Navigation SDKs or turn-by-turn components

2) Get a route from a Directions API

Your app sends:

• Start location
• Destination
• Travel mode: driving, walking, cycling, etc.

The API returns:

• Route geometry (polyline)
• Step-by-step instructions
• Distance/time estimates
• Maneuvers like “turn left,” “merge,” etc.

Example flow:

1. User enters destination
2. App gets current GPS location
3. App requests directions
4. App receives route + steps
5. App draws route on map and starts navigation guidance

3) Render the route on the map

Use the route geometry to:

• Draw a polyline on the map
• Mark start/end points
• Optionally show intermediate waypoints

4) Build navigation guidance

For turn-by-turn behavior, you need to:

• Track live GPS position
• Match user location to the route
• Detect when the user is off-route
• Advance through route steps
• Show next instruction text and distance
• Optionally speak instructions using text-to-speech

Typical UI elements:

• Current maneuver: “Turn right onto Main St.”
• Distance to next turn: “In 300 m”
• Remaining ETA
• Recenter button
• Off-route warning

5) Handle route recalculation

If the user deviates from the route:

• Detect off-route based on distance and heading
• Request a new route from current position to destination
• Replace the active guidance

6) Consider using an SDK instead of building everything yourself

If you want full navigation, use a navigation SDK rather than only a directions API.

Examples:

• Google Navigation SDK / Maps SDK
• Mapbox Navigation SDK
• HERE Navigation
• TomTom Navigation SDK

These can handle:

• GPS tracking
• Route matching
• Voice guidance
• Re-routing
• Lane guidance
• Better UI/UX for navigation

7) Important implementation details

• Request location permissions properly
• Use background location carefully, especially on iOS/Android
• Optimize battery usage
• Cache routes when possible
• Support poor GPS conditions
• Make sure voice instructions are clear and timely

8) Basic architecture

A simple setup looks like this:

• Frontend mobile app
  • map display
  • location tracking
  • route UI
• Directions API
  • returns route and instructions
• Navigation logic
  • step progression
  • off-route detection
  • rerouting
• Optional backend
  • store preferences
  • saved places
  • analytics

9) Example pseudo-flow

User selects destination
→ App gets current location
→ Call directions API
→ Display route on map
→ Start GPS watch
→ Show next instruction
→ Speak instruction
→ Detect arrival or off-route
→ Recalculate if needed

10) Recommended approach

• If you want basic directions: use a map + directions API.
• If you want full navigation: use a dedicated navigation SDK.

If you tell me your stack (iOS, Android, Flutter, React Native, etc.) and which map provider you prefer, I can give you a concrete implementation example.