I have an issue with CoreMotion
and the following code :
let motionManager = CMMotionManager()
It blocks my Mainthread for 4-5 seconds and I don't know why. The problem appears when I updated my iPhone XR to 12.2. It does not block the mainthread with a iPhone 6S on 12.1.3.
I think it may be a hardware problem or iOS version.
Thank you
CoreMotion is doing a lot on his own during init.
Move the initialisation do a different thread.
Edit:
I can confirm the issue with 12.2 on a development iPhone Xs. No issue on a real used device. I see also violation warnings telling CoreMotion tries to access the Applicationstate from a background thread.
However moving the init to a separate thread fixes any UI hangs here. The init of coremotion still does take a while. I created a empty single view application project and changed the ViewController class
class ViewController: UIViewController {
var motionManager: CMMotionManager?
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
view.backgroundColor = UIColor.red
DispatchQueue.global().async {
self.motionManager = CMMotionManager()
DispatchQueue.main.async {
self.view.backgroundColor = UIColor.green
}
}
view.backgroundColor = UIColor.yellow
}
}
Without a separate thread, the red color remains. With a separate thread the color is instant yellow and finally green on the dev XS and instant green on my iPhone 8Plus.
Addition:
Interestingly, without XCode attached, the dev device has no issues. Try to run your code without being connected to the Debugger.
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