diff --git a/doric-android/devkit/src/main/java/pub/doric/devkit/DoricDebugJSEngine.java b/doric-android/devkit/src/main/java/pub/doric/devkit/DoricDebugJSEngine.java
index a8d66b39..7e96f29b 100644
--- a/doric-android/devkit/src/main/java/pub/doric/devkit/DoricDebugJSEngine.java
+++ b/doric-android/devkit/src/main/java/pub/doric/devkit/DoricDebugJSEngine.java
@@ -1,3 +1,18 @@
+/*
+ * Copyright [2019] [Doric.Pub]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package pub.doric.devkit;
 
 import pub.doric.devkit.remote.DoricRemoteJSExecutor;
@@ -9,6 +24,7 @@ public class DoricDebugJSEngine extends DoricJSEngine {
     public DoricDebugJSEngine(WSClient wsClient) {
         super();
         this.wsClient = wsClient;
+        this.getRegistry().registerMonitor(new DoricDevMonitor());
     }
 
     @Override
diff --git a/doric-iOS/Devkit/Classes/DoricDebugDriver.m b/doric-iOS/Devkit/Classes/DoricDebugDriver.m
index 57ced03e..35dc6061 100644
--- a/doric-iOS/Devkit/Classes/DoricDebugDriver.m
+++ b/doric-iOS/Devkit/Classes/DoricDebugDriver.m
@@ -163,12 +163,10 @@ - (DoricAsyncResult *)createContext:(NSString *)contextId script:(NSString *)scr
 
 - (DoricAsyncResult *)destroyContext:(NSString *)contextId {
     DoricAsyncResult *ret = [[DoricAsyncResult alloc] init];
-    __weak typeof(self) _self = self;
+    NSString *theContextId = self.theContextId;
     [self.jsExecutor ensureRunOnJSThread:^{
-        __strong typeof(_self) self = _self;
-        if (!self) return;
         @try {
-            if ([contextId isEqualToString:self.theContextId]) {
+            if ([contextId isEqualToString:theContextId]) {
                 [DoricDev.instance stopDebugging:NO];
             }
             [ret setupResult:@YES];
diff --git a/doric-iOS/Devkit/Classes/DoricDebugJSEngine.m b/doric-iOS/Devkit/Classes/DoricDebugJSEngine.m
index a22a9e0b..8d084419 100644
--- a/doric-iOS/Devkit/Classes/DoricDebugJSEngine.m
+++ b/doric-iOS/Devkit/Classes/DoricDebugJSEngine.m
@@ -23,6 +23,7 @@
 #import "DoricContext.h"
 #import "DoricDebugJSEngine.h"
 #import "DoricRemoteJSExecutor.h"
+#import "DoricDevMonitor.h"
 
 @interface DoricDebugJSEngine ()
 @property(nonatomic, weak) DoricWSClient *wsClient;
@@ -33,6 +34,7 @@ @implementation DoricDebugJSEngine
 - (instancetype)initWithWSClient:(DoricWSClient *)wsClient {
     if (self = [super init]) {
         _wsClient = wsClient;
+        [self.registry registerMonitor:[DoricDevMonitor new]];
     }
     return self;
 }
diff --git a/doric-iOS/Devkit/Classes/DoricDev.h b/doric-iOS/Devkit/Classes/DoricDev.h
index 81d7b402..788b8b8f 100644
--- a/doric-iOS/Devkit/Classes/DoricDev.h
+++ b/doric-iOS/Devkit/Classes/DoricDev.h
@@ -24,7 +24,8 @@
 NS_ASSUME_NONNULL_BEGIN
 
 @interface DoricDev : NSObject
-@property(nonatomic, strong) DoricWSClient *wsClient;
+@property(nonatomic, strong, nullable) DoricWSClient *wsClient;
+
 + (instancetype)instance;
 
 - (void)openDevMode;