Implement isScanning api (#188)

* Implement isScanning api

* Improve IOS scanning api

* Update Readme and Changelog

android/src/main/kotlin/com/navideck/universal_ble/SafeScanner.kt

@@ -36,6 +36,7 @@ class SafeScanner(private val bluetoothManager: BluetoothManager) {
     private val handler = Handler(Looper.myLooper()!!)
     private val startTimes = LinkedList<Long>()
     private var awaitingScan = false
+    private var isScanning = false
 
     fun startScan(filters: List<ScanFilter>, settings: ScanSettings, callback: ScanCallback) {
         val now = System.currentTimeMillis()
@@ -52,7 +53,7 @@ class SafeScanner(private val bluetoothManager: BluetoothManager) {
             }
 
             awaitingScan = true
-            val delay = startTimes.first + EXCESSIVE_SCANNING_PERIOD_MS - now + 2_000
+            val delay = startTimes.first() + EXCESSIVE_SCANNING_PERIOD_MS - now + 2_000
             Log.e(TAG, "startScan: too frequent, schedule auto-start after $delay ms $startTimes")
 
             handler.postDelayed({
@@ -65,8 +66,10 @@ class SafeScanner(private val bluetoothManager: BluetoothManager) {
             startTimes.addLast(now)
             try {
                 bluetoothManager.adapter.bluetoothLeScanner?.startScan(filters, settings, callback)
+                isScanning = true
             } catch (e: Exception) {
                 Log.e(TAG, "Failed to start Scan : $e")
+                isScanning = false
             }
         }
     }
@@ -75,5 +78,10 @@ class SafeScanner(private val bluetoothManager: BluetoothManager) {
         awaitingScan = false
         handler.removeCallbacksAndMessages(null)
         bluetoothManager.adapter.bluetoothLeScanner?.stopScan(callback)
+        isScanning = false
+    }
+
+    fun isScanning(): Boolean {
+        return isScanning || awaitingScan
     }
 }

android/src/main/kotlin/com/navideck/universal_ble/UniversalBle.g.kt

@@ -1,4 +1,4 @@
-// Autogenerated from Pigeon (v26.0.5), do not edit directly.
+// Autogenerated from Pigeon (v26.1.0), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 @file:Suppress("UNCHECKED_CAST", "ArrayInDataClass")
 
@@ -447,6 +447,7 @@ interface UniversalBlePlatformChannel {
   fun disableBluetooth(callback: (Result<Boolean>) -> Unit)
   fun startScan(filter: UniversalScanFilter?)
   fun stopScan()
+  fun isScanning(): Boolean
   fun connect(deviceId: String)
   fun disconnect(deviceId: String)
   fun setNotifiable(deviceId: String, service: String, characteristic: String, bleInputProperty: Long, callback: (Result<Unit>) -> Unit)
@@ -557,6 +558,21 @@ interface UniversalBlePlatformChannel {
           channel.setMessageHandler(null)
         }
       }
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.universal_ble.UniversalBlePlatformChannel.isScanning$separatedMessageChannelSuffix", codec)
+        if (api != null) {
+          channel.setMessageHandler { _, reply ->
+            val wrapped: List<Any?> = try {
+              listOf(api.isScanning())
+            } catch (exception: Throwable) {
+              UniversalBlePigeonUtils.wrapError(exception)
+            }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
       run {
         val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.universal_ble.UniversalBlePlatformChannel.connect$separatedMessageChannelSuffix", codec)
         if (api != null) {

android/src/main/kotlin/com/navideck/universal_ble/UniversalBlePlugin.kt

@@ -187,6 +187,10 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
         safeScanner.stopScan(scanCallback)
     }
 
+    override fun isScanning(): Boolean {
+      return  safeScanner.isScanning()
+    }
+
     override fun connect(deviceId: String) {
         // If already connected, send connected message,
         // if connecting, do nothing