Core Location

Implementation patterns for Core Location, covering authorization strategy, choosing a monitoring approach, accuracy optimization, and background location setup.

When to Use

Use this skill when you're:

• Choosing between When In Use and Always authorization
• Deciding on a monitoring approach (continuous updates, significant-change, or CLMonitor)
• Implementing geofencing or region monitoring
• Setting up background location updates
• Debugging "location not working" issues
• Reviewing location code for anti-patterns

Example Prompts

Questions you can ask your assistant that will draw from this skill:

• "Should I use When In Use or Always authorization?"
• "How should I implement geofencing in my app?"
• "What's the best way to track user location in the background?"
• "Why is my location code draining battery?"
• "How do I upgrade from When In Use to Always authorization?"
• "What accuracy level should I use for a store finder?"
• "How do I handle location authorization denial gracefully?"

What This Skill Provides

Anti-Patterns Prevented

• Premature Always authorization (a 30–60% denial rate)
• Continuous updates for geofencing (10× the battery drain of CLMonitor)
• Ignoring stationary detection (wasted battery)
• No graceful denial handling
• The wrong accuracy for the use case
• Not stopping updates when done
• Ignoring CLServiceSession (iOS 18+)
• Treating reduced accuracy as a toggle you control, when Approximate location silently breaks geofences

Decision Trees

• Authorization strategy (When In Use vs. Always, and the upgrade flow)
• Monitoring strategy (continuous vs. significant-change vs. CLMonitor)
• Accuracy selection (navigation vs. fitness vs. store finder)

Pressure Scenarios

• Pushing back on "just use Always authorization"
• Debugging "location isn't working in the background"
• Fixing "geofence events aren't firing" in production

Checklists and Version Notes

• A pre-release location checklist (Info.plist keys, privacy manifest, authorization, updates, testing)
• A background location setup checklist
• Which APIs need iOS 17 (CLLocationUpdate, CLMonitor) or iOS 18 (CLServiceSession), and the CLLocationManager path for iOS 14–16

Key Pattern

Progressive Authorization (Recommended)

// Start minimal - When In Use
let baseSession = CLServiceSession(authorization: .whenInUse)

// Later, when user creates a location reminder:
let alwaysSession = CLServiceSession(authorization: .always)

// For features needing full accuracy:
let navSession = CLServiceSession(
    authorization: .whenInUse,
    fullAccuracyPurposeKey: "Navigation"
)

Why: Requesting Always authorization up front draws a 30–60% denial rate. Upgrading progressively, once the user understands the value, draws 5–10%.

Documentation Scope

This page documents the core-location skill (in the axiom-location suite), the implementation patterns and decision frameworks your assistant uses when helping you design location features.

Related

• Core Location Reference – API details and code examples for modern Core Location
• Core Location Diagnostics – Symptom-based troubleshooting
• Energy Optimization – Location as a battery subsystem

Resources

WWDC: 2023-10180 (Discover streamlined location updates), 2023-10147 (Meet Core Location Monitor), 2024-10212 (What's new in location authorization)

Docs: /corelocation, /corelocation/clmonitor, /corelocation/cllocationupdate, /corelocation/clservicesession