Wait for writeWithoutResponse completion (#166)

* Wait for writeWithoutResponse request completion on Android

* Wait for writeWithoutResponse request completion on Darwin

* Add WriteWithoutResponse button in example app

* Update changelog and bump version

* Apply suggestions from code review

Co-authored-by: Foti Dim <foti@navideck.com>

---------

Co-authored-by: Foti Dim <foti@navideck.com>

darwin/Classes/UniversalBlePlugin.swift

@@ -36,6 +36,7 @@ private class BleCentralDarwin: NSObject, UniversalBlePlatformChannel, CBCentral
   private var discoveredServicesProgressMap: [String: [UniversalBleService]] = [:]
   private var characteristicReadFutures = [CharacteristicReadFuture]()
   private var characteristicWriteFutures = [CharacteristicWriteFuture]()
+  private var characteristicWriteWithoutResponseFutures = [CharacteristicWriteFuture]()
   private var characteristicNotifyFutures = [CharacteristicNotifyFuture]()
   private var discoverServicesFutures = [DiscoverServicesFuture]()
 
@@ -263,11 +264,12 @@ private class BleCentralDarwin: NSObject, UniversalBlePlatformChannel, CBCentral
     }
     peripheral.writeValue(value.data, for: gattCharacteristic, type: type)
 
+    // Wait for future response
+    let future = CharacteristicWriteFuture(deviceId: deviceId, characteristicId: gattCharacteristic.uuid.uuidStr, serviceId: gattCharacteristic.service?.uuid.uuidStr, result: completion)
     if type == CBCharacteristicWriteType.withResponse {
-      // Wait for future response
-      characteristicWriteFutures.append(CharacteristicWriteFuture(deviceId: deviceId, characteristicId: gattCharacteristic.uuid.uuidStr, serviceId: gattCharacteristic.service?.uuid.uuidStr, result: completion))
+      characteristicWriteFutures.append(future)
     } else {
-      completion(Result.success({}()))
+      characteristicWriteWithoutResponseFutures.append(future)
     }
   }
 
@@ -412,6 +414,16 @@ private class BleCentralDarwin: NSObject, UniversalBlePlatformChannel, CBCentral
     }
   }
 
+  public func peripheralIsReady(toSendWriteWithoutResponse peripheral: CBPeripheral) {
+    characteristicWriteWithoutResponseFutures.removeAll { future in
+      if future.deviceId == peripheral.uuid.uuidString {
+        future.result(Result.success({}()))
+        return true
+      }
+      return false
+    }
+  }
+
   public func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
     characteristicWriteFutures.removeAll { future in
       if future.deviceId == peripheral.uuid.uuidString && future.characteristicId == characteristic.uuid.uuidStr && future.serviceId == characteristic.service?.uuid.uuidStr {