fix compile issue

ios/Classes/FluwxPlugin.m

@@ -67,16 +67,24 @@ BOOL handleOpenURLByFluwx = YES;
 NSObject <FlutterPluginRegistrar> *_fluwxRegistrar;
 
 
-- (instancetype)initWithRegistrar:(NSObject <FlutterPluginRegistrar> *)registrar methodChannel:(FlutterMethodChannel *)flutterMethodChannel {
++ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar> *)registrar {
+    FlutterMethodChannel *channel =
+        [FlutterMethodChannel methodChannelWithName:@"com.jarvanmo/fluwx"
+                                    binaryMessenger:[registrar messenger]];
+    FluwxPlugin *instance = [[FluwxPlugin alloc] initWithChannel:channel];
+    [registrar addApplicationDelegate:instance];
+    [registrar addMethodCallDelegate:instance channel:channel];
+}
+
+- (instancetype)initWithChannel:(FlutterMethodChannel *)channel {
     self = [super init];
     if (self) {
-        _fluwxRegistrar = registrar;
-        _isRunning = NO;
+        _channel = channel;
         _qrauth = [[WechatAuthSDK alloc] init];
         _qrauth.delegate = self;
+        _isRunning = NO;
         thumbnailWidth = 150;
-        _channel = flutterMethodChannel;
-        _attemptToResumeMsgFromWxFlag = false;
+        _attemptToResumeMsgFromWxFlag = NO;
 #if WECHAT_LOGGING
         [WXApi startLogByLevel:WXLogLevelDetail logBlock:^(NSString *log) {
             [self logToFlutterWithDetail:log];
@@ -157,16 +165,6 @@ NSObject <FlutterPluginRegistrar> *_fluwxRegistrar;
     }
 }
 
-+ (void)registerWithRegistrar:(nonnull NSObject<FlutterPluginRegistrar> *)registrar {
-    <#code#>
-}
-
-
-+ (void)registerWithRegistrar:(nonnull NSObject<FlutterPluginRegistrar> *)registrar {
-    <#code#>
-}
-
-
 - (void)openWeChatInvoice:(FlutterMethodCall *)call result:(FlutterResult)result {
 
     NSString *appId = call.arguments[@"appId"];
@@ -1068,8 +1066,8 @@ NSObject <FlutterPluginRegistrar> *_fluwxRegistrar;
             };
         }
 
-        if(channel != nil){
-            [channel invokeMethod:@"onWXShowMessageFromWX" arguments:result];
+        if(_channel != nil){
+            [_channel invokeMethod:@"onWXShowMessageFromWX" arguments:result];
         }
     }