Main Thread Checker: UI API called on a background thread: -[UIApplication applicationState]

[vinodgleecus]

I just implemented this simple method to fetch all available tags/zones

import UIKit
import Parse
import EstimoteProximitySDK

class HomeViewController: UIViewController {

let estimoteCloudCredentials = CloudCredentials(appID: "xxxxxxxx", appToken: "xxxxxxxxxxxxx")
var proximityObserver: ProximityObserver!

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    self.tabBarController?.title = "HOME"
    
    DispatchQueue.main.async {
        self.loadNearByBeacons()
    }
}

private func loadNearByBeacons(){
    
    self.proximityObserver = ProximityObserver(
        credentials: estimoteCloudCredentials,
        onError: { error in
            print("proximity observer error: \(error)")
    })
    
    let blueberryZone = ProximityZone(tag: "DevOffice", range: ProximityRange.custom(desiredMeanTriggerDistance: 1.0)!)
    blueberryZone.onEnter = { zoneContext in
        print("Entered near range of tag 'DevOffice'. DeviceIdentifier: \(zoneContext.deviceIdentifier)")
    }
    blueberryZone.onExit = { zoneContext in
        print("Exited near range of tag 'DevOffice'. DeviceIdentifier: \(zoneContext.deviceIdentifier)")
    }
    
    blueberryZone.onContextChange = { contexts in
        print("Now in range of \(contexts.count) contexts")
    }
    // ... etc. You can define as many zones as you need.
    // Start proximity observation
    //self.observe.startObserving([blueberryZone])
    self.proximityObserver.startObserving([blueberryZone])
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.tabBarController?.title = "HOME"
}

/*
// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    // Get the new view controller using segue.destination.
    // Pass the selected object to the new view controller.
}
*/

}

I'm getting this crash while fetching NearbyTags from Cloud

Main Thread Checker: UI API called on a background thread: -[UIApplication applicationState]
PID: 457, TID: 60500, Thread name: com.apple.CoreMotion.MotionThread, Queue name: com.apple.root.default-qos.overcommit, QoS: 0
Backtrace:
4 libobjc.A.dylib 0x000000019c7476f4 + 56
5 CoreMotion 0x00000001a2e91638 CoreMotion + 292408
6 CoreMotion 0x00000001a2e91b68 CoreMotion + 293736
7 CoreMotion 0x00000001a2e91a78 CoreMotion + 293496
8 CoreMotion 0x00000001a2ebf8a8 CoreMotion + 481448
9 CoreMotion 0x00000001a2ebf8ec CoreMotion + 481516
10 CoreFoundation 0x000000019d4d378c + 28
11 CoreFoundation 0x000000019d4d3074 + 276
12 CoreFoundation 0x000000019d4ce368 + 2276
13 CoreFoundation 0x000000019d4cd764 CFRunLoopRunSpecific + 452
14 CoreFoundation 0x000000019d4ce498 CFRunLoopRun + 84
15 CoreMotion 0x00000001a2ebf280 CoreMotion + 479872
16 libsystem_pthread.dylib 0x000000019d14d920 + 132
17 libsystem_pthread.dylib 0x000000019d14d87c _pthread_start + 48
18 libsystem_pthread.dylib 0x000000019d155dcc thread_start + 4
2019-05-20 16:53:40.004753+0530 Critik[457:60500] [reports] Main Thread Checker: UI API called on a background thread: -[UIApplication applicationState]
PID: 457, TID: 60500, Thread name: com.apple.CoreMotion.MotionThread, Queue name: com.apple.root.default-qos.overcommit, QoS: 0
Backtrace:
4 libobjc.A.dylib 0x000000019c7476f4 + 56
5 CoreMotion 0x00000001a2e91638 CoreMotion + 292408
6 CoreMotion 0x00000001a2e91b68 CoreMotion + 293736
7 CoreMotion 0x00000001a2e91a78 CoreMotion + 293496
8 CoreMotion 0x00000001a2ebf8a8 CoreMotion + 481448
9 CoreMotion 0x00000001a2ebf8ec CoreMotion + 481516
10 CoreFoundation 0x000000019d4d378c + 28
11 CoreFoundation 0x000000019d4d3074 + 276
12 CoreFoundation 0x000000019d4ce368 + 2276
13 CoreFoundation 0x000000019d4cd764 CFRunLoopRunSpecific + 452
14 CoreFoundation 0x000000019d4ce498 CFRunLoopRun + 84
15 CoreMotion 0x00000001a2ebf280 CoreMotion + 479872
16 libsystem_pthread.dylib 0x000000019d14d920 + 132
17 libsystem_pthread.dylib 0x000000019d14d87c _pthread_start + 48
18 libsystem_pthread.dylib 0x000000019d155dcc thread_start + 4

[vinodgleecus]

can anyone please respond to this?

[chwastek]

hey @vinodgleecus
firstly sorry for not responding for so long!
secondly: could you share bit more?

• does it happen all the time/sometimes?
• which version of the SDK are you using?
• do you get logs from Proximity SDK?
• are you 100% sure that you have at least one device with DevOffice tag?

Regards

[vinodgleecus]

yes it happens every time
pod 'EstimoteProximitySDK','~> 1.2.1'
no, I didn't any logs
yes Am 100% Sure

[divrt-anvesht]

I too have same problem "Main Thread Checker: UI API called on a background thread: -[UIApplication applicationState]" in my current App Store app. @Estimote could you please fix this issue ASAP. I am using EstimoteProximitySDK (1.4.1) in my app.
This weird bug in iPhone X and later devices making app stuck for a while....