iOS Core Bluetooth : Getting API MISUSE Warning

Question

I am writing a test app in iOS 7 with the Core Bluetooth API. When I am testing the application I found that I am getting the following warning message:

TestBluetooth[626:60b] CoreBluetooth[API MISUSE] can only accept commands while in the powered on state

Later I debugged app and found that, warning is coming from the following line of code:

[manager scanForPeripheralsWithServices:array options:scanOptions];

So can anyone please tell me why I am getting this message in the console?

There are bluetooth 4.0 android devices around me, but this app is not discovering them as peripheral device. So why it is not discovering bluetooth 4.0 LE Android devices as peripherals?

You need to check the `CBCentralManager` `state` property before: https://developer.apple.com/library/ios/documentation/CoreBluetooth/Reference/CBCentralManager_Class/translated_content/CBCentralManager.html#//apple_ref/occ/instp/CBCentralManager/state — Larme, Apr 28 '14 at 10:43
For anyone trying to solve the same problem for flutter (flutter_blue_plus package) looking for hints here, you need to set up a stream subscription for [bluetooth state](https://pub.dev/documentation/flutter_blue_plus/latest/flutter_blue_plus/BluetoothDevice/state.html) — Shawn Ashton, Jun 30 '23 at 19:18

score 83 · Accepted Answer · edited Apr 11 '18 at 06:50

83

You have to wait until the [-CBCentralManagerDelegate centralManagerDidUpdateState:] callback has been called. And then, verify that the state is PoweredOn before you start scanning for peripherals.

edited Apr 11 '18 at 06:50

viral

4,168
5
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answered May 12 '14 at 08:34

Etan

17,014
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1

I've created a tool to help debug the API Misuse errors: https://github.com/nrbrook/NBCoreBluetoothAPIMisuseGuard – Nick May 03 '16 at 16:30

score 4 · Answer 2 · edited Apr 11 '18 at 06:52

Please use the following code to solve the warning:

(You can reference to the code in https://github.com/luoxubin/BlueTooth4.0)

if (bluetoothPowerOn) {
    [self.centralManager scanForPeripheralsWithServices:[serviceIDs copy] options:@{CBCentralManagerScanOptionAllowDuplicatesKey:@(NO)}];
}

-(void)centralManagerDidUpdateState:(CBCentralManager *)central{

    switch (central.state) {

        case CBManagerStatePoweredOn:
        {
            bluetoothPowerOn = YES;    //new code
            [self start];
            break;
        }

        default:
        {    
            bluetoothPowerOn = NO;   //new code
            [self stopScan:[NSError hardwareStatusErrorWithMessage:@"Cannot open Bluetooth, please check the setting." hardwareStatus:central.state]];    
            break;
        }
    }
}

score 3 · Answer 3 · answered Oct 15 '18 at 10:15

Do scan when bluetooth is poweredOn:

func centralManagerDidUpdateState(_ central: CBCentralManager) {
        switch central.state {
        case .unknown:
            print("unknown")
        case .resetting:
            print("resetting")
        case .unsupported:
            print("unsupported")
        case .unauthorized:
            print("unauthorized")
        case .poweredOff:
            print("poweredOff")
            centralManager?.stopScan()
        case .poweredOn:
            print("poweredOn")
            centralManager?.scanForPeripherals(withServices: nil, options: nil)
        }
    }

Yogesh Rathore · Answer 4 · 2023-06-20T05:23:01.323

-1

turn on iphone Bluetooth resolve my problem. after turn on bluetooth not getting below warning. CoreBluetooth[API MISUSE] can only accept commands while in the powered on state

edited Jun 20 '23 at 05:23

answered Dec 21 '21 at 13:32

Yogesh Rathore

147
1
7

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iOS Core Bluetooth : Getting API MISUSE Warning

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