修复读取 CCCD 报错的问题，写入时更新特征值 (#50)

* 修复 CCCD 无法读取的问题

* 优化代码

* 调整部分必需参数为可空参数

* 调整接口

* 写入时更新特征值

* 调整接口

* 适配新接口

* 调整依赖项

bluetooth_low_energy_darwin/lib/src/my_api.dart

@@ -203,17 +203,13 @@ extension MyGattDescriptorX on MyGattDescriptor {
 }
 
 extension MyGattCharacteristicX on MyGattCharacteristic {
-  MyGattCharacteristicArgs toArgs() {
+  MyGattCharacteristicArgs toArgs(List<MyGattDescriptorArgs> descriptorsArgs) {
     final hashCodeArgs = hashCode;
     final uuidArgs = uuid.toArgs();
     final propertyNumbersArgs = properties.map((property) {
       final propertyArgs = property.toArgs();
       return propertyArgs.index;
     }).toList();
-    final descriptorsArgs = descriptors
-        .cast<MyGattDescriptor>()
-        .map((descriptor) => descriptor.toArgs())
-        .toList();
     return MyGattCharacteristicArgs(
       hashCodeArgs: hashCodeArgs,
       uuidArgs: uuidArgs,
@@ -224,13 +220,9 @@ extension MyGattCharacteristicX on MyGattCharacteristic {
 }
 
 extension MyGattServiceX on MyGattService {
-  MyGattServiceArgs toArgs() {
+  MyGattServiceArgs toArgs(List<MyGattCharacteristicArgs> characteristicsArgs) {
     final hashCodeArgs = hashCode;
     final uuidArgs = uuid.toArgs();
-    final characteristicsArgs = characteristics
-        .cast<MyGattCharacteristic>()
-        .map((characteristic) => characteristic.toArgs())
-        .toList();
     return MyGattServiceArgs(
       hashCodeArgs: hashCodeArgs,
       uuidArgs: uuidArgs,

bluetooth_low_energy_darwin/lib/src/my_peripheral_manager.dart

@@ -65,14 +65,22 @@ class MyPeripheralManager extends PeripheralManager
     if (service is! MyGattService) {
       throw TypeError();
     }
-    final serviceArgs = service.toArgs();
-    final hashCodeArgs = serviceArgs.hashCodeArgs;
-    logger.info('addService: $hashCodeArgs');
+    final characteristics = <int, MyGattCharacteristic>{};
+    final characteristicsArgs = <MyGattCharacteristicArgs>[];
+    for (var characteristic in service.characteristics) {
+      final descriptorsArgs = <MyGattDescriptorArgs>[];
+      for (var descriptor in characteristic.descriptors) {
+        final descriptorArgs = descriptor.toArgs();
+        descriptorsArgs.add(descriptorArgs);
+      }
+      final characteristicArgs = characteristic.toArgs(descriptorsArgs);
+      characteristicsArgs.add(characteristicArgs);
+      characteristics[characteristicArgs.hashCodeArgs] = characteristic;
+    }
+    final serviceArgs = service.toArgs(characteristicsArgs);
+    logger.info('addService: $serviceArgs');
     await _api.addService(serviceArgs);
-    _characteristics[hashCodeArgs] = {
-      for (var characteristics in service.characteristics)
-        characteristics.hashCode: characteristics
-    };
+    _characteristics[serviceArgs.hashCodeArgs] = characteristics;
   }
 
   @override
@@ -304,7 +312,8 @@ class MyPeripheralManager extends PeripheralManager
     MyGattCharacteristic characteristic,
     Uint8List value,
   ) async {
-    final trimmedValue = value.trimGATT();
+    characteristic.value = value;
+    final trimmedValue = characteristic.value;
     final eventArgs = GattCharacteristicWrittenEventArgs(
       central,
       characteristic,