iOS MissingPluginException(No implementation found for method listen on channel volume_watcher_event)

[spring321]

VolumeWatcher.addListener((volume) {
Logger().wtf('进入了监听音量键: $volume');
});

[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: MissingPluginException(No implementation found for method listen on channel volume_watcher_event)
#0 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:320:7)

#1 EventChannel.receiveBroadcastStream. (package:flutter/src/services/platform_channel.dart:664:9)

[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: MissingPluginException(No implementation found for method getCurrentVolume on channel volume_watcher_method)
#0 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:320:7)

#1 VolumeWatcher.getCurrentVolume (package:volume_watcher/volume_watcher.dart:92:9)

#2 VolumeWatcher.addListener. (package:volume_watcher/volume_watcher.dart:51:29)