Crashes immediately on MIDI event (or, what am I missing)

[apaleslimghost]

I created an empty Swift project, and in AppDelegate.application(_:didFinishLaunchingWithOptions:) added _ = MIKMIDIConnectionManager(name: "test"). That's it. As soon as the first MIDI event comes in the app crashes with EXC_BAD_ACCESS. I did wonder if it was #213, but I can reproduce in 1.6.2 and master.

Since I've no idea what I'm doing here, what's the absolute minimum I need to set up to start receiving MIDI events? Do I need MIKMIDIConnectionManager? Should registering the delegate be enough?

Is there an example project (in Swift!) anywhere?

[armadsen]

Do you mind zipping up your project and sending it to me (andrew@openreelsoftware.com)? What you've described should work. I don't have a MIDI device handy to test with the moment, but will later tonight.

[armadsen]

I was able to reproduce this. The problem here is that the MIKMIDIConnectionManager you're creating is being deallocated nearly immediately because you're not storing a strong reference to it (you're not even putting it in a variable). This is exposing a bug in MIKMIDI that causes a crash. (I've opened issue #215 for this, and will push a fix shortly.)

However, you need a little more than that to actually receive events. Try this:

class AppDelegate: UIResponder, UIApplicationDelegate {

	var window: UIWindow?

	let connectionManager = MIKMIDIConnectionManager(name: "test")
	
	func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
		
		connectionManager.eventHandler = { (source, messages) in
			print("Received MIDI messages: \(messages)")
		}
		
		return true
	}
}

[armadsen]

The crash you saw should be fixed in master, but you'll still need to make sure you keep a strong reference to the connection manager (e.g. using a property as in my example code above) in order to actually receive events.

[apaleslimghost]

Αh, thanks. Weak references always catch me out 😞