CODEWITHSUNDEEP
iosobjective-cbluetoothbluetooth-lowenergycore-bluetooth
Jongers
Jongers

Reputation: 681

Core Bluetooth scan for peripherals while the phone's screen is off

I need to keep scanning for broadcasts from peripherals while the app is in background and when the phone's screen is off. Scanning from background was successful but I can't scan (can't trigger didDiscoverPeripheral) broadcasts when the phone' screen is off.

So far I've implemented beginBackgroundTaskWithExpirationHandler inside applicationDidEnterBackground and that's how I am able to scan in background. So how should I do this?

Upvotes: 1

Views: 1370

Answers (1)

akashlal.com
akashlal.com

Reputation: 366

This is not possible. When you tick 'Uses Bluetooth LE accessories' and 'Acts as a Bluetooth LE accessory', when iPhone screen light is turned off, core bluetooth framework stops advertising and scanning. It resumes advertising/scanning once the screen light turns back on. That's the maximum possible achievable scenario in iOS.

If you want to take this further, you can use beginBackgroundTaskWithExpirationHandler - https://developer.apple.com/documentation/uikit/uiapplication/1623031-beginbackgroundtaskwithexpiratio but that works hardly for 3 minutes. Those 3 minutes start as soon as the app goes from foreground to background.

For saving battery, iOS seems to automatically turn off the BLE hardware and it goes back on as soon as the device moves/screen wakes up. Because when screen is off, user isn't using the iPhone anyway.

Edit: Unless a device is connected, like a headphone- Though not advertising, existing connected devices can share data.

Upvotes: 3

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