The Issue

iOS 18 CoreBluetooth – scanForPeripherals method with a defined CBUUID is not detecting iPhone peripherals advertising in the background state.

Setup

• iPhone A (peripheral) – Advertising a service with a specific CBUUID myServiceUUID
• iPhone B (central) – Scanning using the method sCentralManager.scanForPeripherals(withServices: [myServiceUUID])

Test Cases

1. iPhone B (with iOS 18) – detects iPhone A in the foreground state (app open in the foreground)
2. iPhone B (with iOS 18) – FAILS TO detect iPhone A in the background state (app in background; not terminated)
3. iPhone B (with iOS 17 and below) – detects iPhone A in both foreground and background states

FYI

• iPhone A could be any version of iOS
• Test Case 2 is the ISSUE!