CoreBluetooth on Mac Command line application

Question

I'm trying to build a Command Line app that uses CoreBluetooth. Problem is, it doesn't work on command line apps.

I've moved the my CoreBluetooth code (a class that implements the CBCentralManagerDelegate protocol - let's call this class myBLEManager) from the Command Line app project to another Mac OS GUI App.

I ran some tests in ViewDidLoad() -- supersample, I just init a myBLEManager that creates an instance of CBCentralManager on initialization, then calls scanForPeripherals.

This is what I do in both the CLI and GUI projects. Difference is centralManagerDidUpdateState never gets called in the CLI project. but it does in the GUI Mac app.

Do you want to post an answer ? Or should I when done ? up to you — kmn, Mar 06 '17 at 20:20
@kmn could you update the answer to show a more detailed example of your main class and your myBLEManager class? — angryip, Mar 26 '17 at 03:18

score 7 · Accepted Answer · edited Mar 07 '17 at 13:51

7

Callbacks in most Apple frameworks are delivered through your application's main run loop. If your command-line tool does not have a run loop, it cannot receive callbacks that are sent this way.

Without a runloop, the only way for the framework to invoke your callback would be to run it on another thread, which could lead to weird behavior in an application that didn't expect that.

It's sufficient to add:

let runLoop = RunLoop.current
let distantFuture = Date.distantFuture
while running == true && runLoop.run(mode: RunLoopMode.defaultRunLoopMode, before: distantFuture) {

}

edited Mar 07 '17 at 13:51

kmn

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answered Mar 06 '17 at 20:34

could you update the answer to show a more detailed example of your main class and your myBLEManager class? – angryip Mar 25 '17 at 21:13
@angryip I didn't write the program. – Mar 26 '17 at 03:04
fair enough, i'll reach out to the author – angryip Mar 26 '17 at 03:18
Here's an example I found that uses RunLoop to access CoreLocation from a command line application: https://gist.github.com/cmittendorf/2c6eefc6dd128b323428 – Sam Sep 21 '18 at 12:16

score 0 · Answer 2 · answered Jul 14 '22 at 14:48

In Swift 5+ this is the syntax for a Runloop:

import Foundation

let runLoop = RunLoop.current
let distantFuture = Date.distantFuture
var shouldKeepRunning = true

while shouldKeepRunning == true && runLoop.run(mode: RunLoop.Mode.default, before: distantFuture) {
    
}

CoreBluetooth on Mac Command line application

2 Answers2

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