diff --git a/Android/MMKV/gradle.properties b/Android/MMKV/gradle.properties
index 17ceb0d4..489d64f9 100644
--- a/Android/MMKV/gradle.properties
+++ b/Android/MMKV/gradle.properties
@@ -12,6 +12,6 @@ org.gradle.jvmargs=-Xmx1536m
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
 
-VERSION_NAME_PREFIX=1.0.14
+VERSION_NAME_PREFIX=1.0.15
 #VERSION_NAME_SUFFIX=-SNAPSHOT
 VERSION_NAME_SUFFIX=
\ No newline at end of file
diff --git a/Android/MMKV/mmkv/src/main/cpp/MMKV.cpp b/Android/MMKV/mmkv/src/main/cpp/MMKV.cpp
index b0219e44..f1af2904 100644
--- a/Android/MMKV/mmkv/src/main/cpp/MMKV.cpp
+++ b/Android/MMKV/mmkv/src/main/cpp/MMKV.cpp
@@ -660,7 +660,7 @@ bool MMKV::ensureMemorySize(size_t newSize) {
                 return false;
             }
         } else {
-            size_t avgItemSize = lenNeeded / m_dic.size();
+            size_t avgItemSize = lenNeeded / std::max<size_t>(1, m_dic.size());
             size_t futureUsage = avgItemSize * std::max<size_t>(8, (m_dic.size() + 1) / 2);
             // 1. no space for a full rewrite, double it
             // 2. or space is not large enough for future usage, double it to avoid frequently full rewrite
diff --git a/Android/MMKV/mmkv/src/main/cpp/native-bridge.cpp b/Android/MMKV/mmkv/src/main/cpp/native-bridge.cpp
index aedc3709..2964f47a 100644
--- a/Android/MMKV/mmkv/src/main/cpp/native-bridge.cpp
+++ b/Android/MMKV/mmkv/src/main/cpp/native-bridge.cpp
@@ -32,9 +32,10 @@ static jclass g_cls = nullptr;
 static jfieldID g_fileID = nullptr;
 static jmethodID g_callbackOnCRCFailID = nullptr;
 static jmethodID g_callbackOnFileLengthErrorID = nullptr;
-static JNIEnv *g_currentEnv = nullptr;
+static JavaVM *g_currentJVM = nullptr;
 
 extern "C" JNIEXPORT JNICALL jint JNI_OnLoad(JavaVM *vm, void *reserved) {
+    g_currentJVM = vm;
     JNIEnv *env;
     if (vm->GetEnv(reinterpret_cast<void **>(&env), JNI_VERSION_1_6) != JNI_OK) {
         return -1;
@@ -138,20 +139,34 @@ static jobjectArray vector2jarray(JNIEnv *env, const vector<string> &arr) {
     return nullptr;
 }
 
+static JNIEnv *getCurrentEnv() {
+    if (g_currentJVM) {
+        JNIEnv *currentEnv = nullptr;
+        auto ret = g_currentJVM->GetEnv(reinterpret_cast<void **>(&currentEnv), JNI_VERSION_1_6);
+        if (ret == JNI_OK) {
+            return currentEnv;
+        } else {
+            MMKVError("fail to get current JNIEnv: %d", ret);
+        }
+    }
+    return nullptr;
+}
+
 MMKVRecoverStrategic onMMKVCRCCheckFail(const std::string &mmapID) {
-    if (g_currentEnv && g_callbackOnCRCFailID) {
-        jstring str = string2jstring(g_currentEnv, mmapID);
-        auto strategic = g_currentEnv->CallStaticIntMethod(g_cls, g_callbackOnCRCFailID, str);
+    auto currentEnv = getCurrentEnv();
+    if (g_currentJVM && g_callbackOnCRCFailID) {
+        jstring str = string2jstring(currentEnv, mmapID);
+        auto strategic = currentEnv->CallStaticIntMethod(g_cls, g_callbackOnCRCFailID, str);
         return static_cast<MMKVRecoverStrategic>(strategic);
     }
     return OnErrorDiscard;
 }
 
 MMKVRecoverStrategic onMMKVFileLengthError(const std::string &mmapID) {
-    if (g_currentEnv && g_callbackOnFileLengthErrorID) {
-        jstring str = string2jstring(g_currentEnv, mmapID);
-        auto strategic =
-            g_currentEnv->CallStaticIntMethod(g_cls, g_callbackOnFileLengthErrorID, str);
+    auto currentEnv = getCurrentEnv();
+    if (currentEnv && g_callbackOnFileLengthErrorID) {
+        jstring str = string2jstring(currentEnv, mmapID);
+        auto strategic = currentEnv->CallStaticIntMethod(g_cls, g_callbackOnFileLengthErrorID, str);
         return static_cast<MMKVRecoverStrategic>(strategic);
     }
     return OnErrorDiscard;
@@ -159,7 +174,6 @@ MMKVRecoverStrategic onMMKVFileLengthError(const std::string &mmapID) {
 
 extern "C" JNIEXPORT JNICALL jlong Java_com_tencent_mmkv_MMKV_getMMKVWithID(
     JNIEnv *env, jobject obj, jstring mmapID, jint mode, jstring cryptKey) {
-    g_currentEnv = env;
     MMKV *kv = nullptr;
     if (!mmapID) {
         return (jlong) kv;
@@ -181,7 +195,6 @@ extern "C" JNIEXPORT JNICALL jlong Java_com_tencent_mmkv_MMKV_getMMKVWithID(
 
 extern "C" JNIEXPORT JNICALL jlong Java_com_tencent_mmkv_MMKV_getMMKVWithIDAndSize(
     JNIEnv *env, jobject obj, jstring mmapID, jint size, jint mode, jstring cryptKey) {
-    g_currentEnv = env;
     MMKV *kv = nullptr;
     if (!mmapID || size < 0) {
         return (jlong) kv;
@@ -204,7 +217,6 @@ extern "C" JNIEXPORT JNICALL jlong Java_com_tencent_mmkv_MMKV_getDefaultMMKV(JNI
                                                                              jobject obj,
                                                                              jint mode,
                                                                              jstring cryptKey) {
-    g_currentEnv = env;
     MMKV *kv = nullptr;
 
     if (cryptKey != nullptr) {
@@ -222,7 +234,6 @@ extern "C" JNIEXPORT JNICALL jlong Java_com_tencent_mmkv_MMKV_getDefaultMMKV(JNI
 
 extern "C" JNIEXPORT JNICALL jlong Java_com_tencent_mmkv_MMKV_getMMKVWithAshmemFD(
     JNIEnv *env, jobject obj, jstring mmapID, jint fd, jint metaFD, jstring cryptKey) {
-    g_currentEnv = env;
     MMKV *kv = nullptr;
     if (!mmapID || fd < 0 || metaFD < 0) {
         return (jlong) kv;
diff --git a/Android/MMKV/mmkv/src/main/java/com/tencent/mmkv/MMKV.java b/Android/MMKV/mmkv/src/main/java/com/tencent/mmkv/MMKV.java
index 460b431a..94decd0e 100644
--- a/Android/MMKV/mmkv/src/main/java/com/tencent/mmkv/MMKV.java
+++ b/Android/MMKV/mmkv/src/main/java/com/tencent/mmkv/MMKV.java
@@ -304,8 +304,7 @@ public <T extends Parcelable> T decodeParcelable(String key, Class<T> tClass) {
     }
 
     @SuppressWarnings("unchecked")
-    public <T extends Parcelable>
-        T decodeParcelable(String key, Class<T> tClass, T defaultValue) {
+    public <T extends Parcelable> T decodeParcelable(String key, Class<T> tClass, T defaultValue) {
         if (tClass == null) {
             return defaultValue;
         }
diff --git a/Android/MMKV/mmkvdemo/build.gradle b/Android/MMKV/mmkvdemo/build.gradle
index 371d22ce..9bfb29cd 100644
--- a/Android/MMKV/mmkvdemo/build.gradle
+++ b/Android/MMKV/mmkvdemo/build.gradle
@@ -63,8 +63,8 @@ repositories {
 dependencies {
     implementation fileTree(include: ['*.jar'], dir: 'libs')
 //    implementation project(':mmkv')
-    implementation 'com.tencent:mmkv:1.0.14'
-//    implementation 'com.tencent:mmkv-static:1.0.14'
+    implementation 'com.tencent:mmkv:1.0.15'
+//    implementation 'com.tencent:mmkv-static:1.0.15'
     implementation 'com.android.support:appcompat-v7:28.0.0'
     implementation 'com.android.support.constraint:constraint-layout:1.1.3'
     testImplementation 'junit:junit:4.12'
diff --git a/Android/MMKV/mmkvdemo/src/main/java/com/tencent/mmkvdemo/MainActivity.java b/Android/MMKV/mmkvdemo/src/main/java/com/tencent/mmkvdemo/MainActivity.java
index 658ac643..8ec6f5a9 100644
--- a/Android/MMKV/mmkvdemo/src/main/java/com/tencent/mmkvdemo/MainActivity.java
+++ b/Android/MMKV/mmkvdemo/src/main/java/com/tencent/mmkvdemo/MainActivity.java
@@ -69,6 +69,8 @@ public void onClick(View v) {
             }
         });
 
+        //testHolderForMultiThread();
+
         //prepareInterProcessAshmem();
         //prepareInterProcessAshmemByContentProvider(KEY_1);
 
@@ -330,6 +332,29 @@ private void testInterProcessReKey() {
         prepareInterProcessAshmemByContentProvider(KEY_2);
     }
 
+    private void testHolderForMultiThread() {
+        final int COUNT = 1;
+        final int THREAD_COUNT = 1;
+        final String ID = "Hotel";
+        final String KEY = "California";
+        final String VALUE = "You can checkout any time you like, but you can never leave.";
+
+        final MMKV mmkv = MMKV.mmkvWithID(ID);
+        Runnable task = new Runnable() {
+            public void run() {
+                for (int i = 0; i < COUNT; ++i) {
+                    mmkv.putString(KEY, VALUE);
+                    mmkv.getString(KEY, null);
+                    mmkv.remove(KEY);
+                }
+            }
+        };
+
+        for (int i = 0; i < THREAD_COUNT; ++i) {
+            new Thread(task, "MMKV-" + i).start();
+        }
+    }
+
     @Override
     public MMKVRecoverStrategic onMMKVCRCCheckFail(String mmapID) {
         return MMKVRecoverStrategic.OnErrorRecover;
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 23ec9075..5d24c000 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,22 @@
 # MMKV Change Log
 
+## v1.0.15 / 2018-12-13
+### iOS / macOS
+What's new  
+
+* Storing **NSString/NSData/NSDate** directly by calling `setString`/`getSring`, `setData`/`getData`, `setDate`/getDate`.
+* Fix a potencial crash due to divided by zero.
+
+
+### Android
+What's new  
+
+* Fix a stack overflow crash due to the **callback** feature introduced by v1.0.13.
+* Fix a potencial crash due to divided by zero.
+
+### Win32
+MMKV for Win32 in under construction. Hopefully will come out in next release. For those who are interested, check out branch `dev_win32` for the latest development.
+
 ## v1.0.14 / 2018-11-30
 ### iOS / macOS
 What's new  
diff --git a/README.md b/README.md
index 44f5d5a3..d7ab1627 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
-[![license](https://img.shields.io/badge/license-BSD_3-brightgreen.svg?style=flat)](https://github.com/Tencent/MMKV/blob/master/LICENSE.txt)
+[![license](https://img.shields.io/badge/license-BSD_3-brightgreen.svg?style=flat)](https://github.com/Tencent/MMKV/blob/master/LICENSE.TXT)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://github.com/Tencent/MMKV/pulls)
-[![Release Version](https://img.shields.io/badge/release-1.0.14-brightgreen.svg)](https://github.com/Tencent/MMKV/releases)
+[![Release Version](https://img.shields.io/badge/release-1.0.15-brightgreen.svg)](https://github.com/Tencent/MMKV/releases)
 [![Platform](https://img.shields.io/badge/Platform-%20iOS%20%7C%20Android-brightgreen.svg)](https://github.com/Tencent/MMKV/wiki/home)
 
 中文版本请参看[这里](./readme_cn.md)
@@ -75,8 +75,8 @@ Add the following lines to `build.gradle` on your app module:
 
 ```gradle
 dependencies {
-    implementation 'com.tencent:mmkv:1.0.14'
-    // replace "1.0.14" with any available version
+    implementation 'com.tencent:mmkv:1.0.15'
+    // replace "1.0.15" with any available version
 }
 ```
 
diff --git a/iOS/MMKV/MMKV/MMKV.h b/iOS/MMKV/MMKV/MMKV.h
index 6b07c6fb..5460b11a 100644
--- a/iOS/MMKV/MMKV/MMKV.h
+++ b/iOS/MMKV/MMKV/MMKV.h
@@ -39,8 +39,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (BOOL)reKey:(nullable NSData *)newKey NS_SWIFT_NAME(reset(cryptKey:));
 - (nullable NSData *)cryptKey;
 
-// object: NSString/NSData/NSDate/id<NSCoding>
-- (BOOL)setObject:(nullable id)object forKey:(NSString *)key NS_SWIFT_NAME(set(_:forKey:));
+- (BOOL)setObject:(nullable NSObject<NSCoding> *)object forKey:(NSString *)key NS_SWIFT_NAME(set(_:forKey:));
 
 - (BOOL)setBool:(BOOL)value forKey:(NSString *)key NS_SWIFT_NAME(set(_:forKey:));
 
@@ -56,6 +55,12 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (BOOL)setDouble:(double)value forKey:(NSString *)key NS_SWIFT_NAME(set(_:forKey:));
 
+- (BOOL)setString:(NSString *)value forKey:(NSString *)key NS_SWIFT_NAME(set(_:forKey:));
+
+- (BOOL)setDate:(NSDate *)value forKey:(NSString *)key NS_SWIFT_NAME(set(_:forKey:));
+
+- (BOOL)setData:(NSData *)value forKey:(NSString *)key NS_SWIFT_NAME(set(_:forKey:));
+
 - (nullable id)getObjectOfClass:(Class)cls forKey:(NSString *)key NS_SWIFT_NAME(object(of:forKey:));
 
 - (BOOL)getBoolForKey:(NSString *)key __attribute__((swift_name("bool(forKey:)")));
@@ -79,6 +84,15 @@ NS_ASSUME_NONNULL_BEGIN
 - (double)getDoubleForKey:(NSString *)key NS_SWIFT_NAME(double(forKey:));
 - (double)getDoubleForKey:(NSString *)key defaultValue:(double)defaultValue NS_SWIFT_NAME(double(forKey:defaultValue:));
 
+- (nullable NSString *)getStringForKey:(NSString *)key NS_SWIFT_NAME(string(forKey:));
+- (nullable NSString *)getStringForKey:(NSString *)key defaultValue:(nullable NSString *)defaultValue NS_SWIFT_NAME(string(forKey:defaultValue:));
+
+- (nullable NSDate *)getDateForKey:(NSString *)key NS_SWIFT_NAME(date(forKey:));
+- (nullable NSDate *)getDateForKey:(NSString *)key defaultValue:(nullable NSDate *)defaultValue NS_SWIFT_NAME(date(forKey:defaultValue:));
+
+- (nullable NSData *)getDataForKey:(NSString *)key NS_SWIFT_NAME(data(forKey:));
+- (nullable NSData *)getDataForKey:(NSString *)key defaultValue:(nullable NSData *)defaultValue NS_SWIFT_NAME(data(forKey:defaultValue:));
+
 - (BOOL)containsKey:(NSString *)key NS_SWIFT_NAME(contains(key:));
 
 - (size_t)count;
diff --git a/iOS/MMKV/MMKV/MMKV.mm b/iOS/MMKV/MMKV/MMKV.mm
index 06fb16d5..512e5c58 100644
--- a/iOS/MMKV/MMKV/MMKV.mm
+++ b/iOS/MMKV/MMKV/MMKV.mm
@@ -524,7 +524,7 @@ - (BOOL)ensureMemorySize:(size_t)newSize {
 		static const int offset = pbFixed32Size(0);
 		NSData *data = [MiniPBCoder encodeDataWithObject:m_dic];
 		size_t lenNeeded = data.length + offset + newSize;
-		size_t avgItemSize = lenNeeded / m_dic.count;
+		size_t avgItemSize = lenNeeded / std::max<size_t>(1, m_dic.count);
 		size_t futureUsage = avgItemSize * std::max<size_t>(8, m_dic.count / 2);
 		// 1. no space for a full rewrite, double it
 		// 2. or space is not large enough for future usage, double it to avoid frequently full rewrite
@@ -619,7 +619,7 @@ - (BOOL)writeAcutalSize:(size_t)actualSize {
 	return YES;
 }
 
-- (BOOL)setData:(NSData *)data forKey:(NSString *)key {
+- (BOOL)setRawData:(NSData *)data forKey:(NSString *)key {
 	if (data.length <= 0 || key.length <= 0) {
 		return NO;
 	}
@@ -682,7 +682,7 @@ - (BOOL)appendData:(NSData *)data forKey:(NSString *)key {
 	}
 }
 
-- (NSData *)getDataForKey:(NSString *)key {
+- (NSData *)getRawDataForKey:(NSString *)key {
 	CScopedLock lock(m_lock);
 	[self checkLoadData];
 	return [m_dic objectForKey:key];
@@ -900,7 +900,7 @@ - (BOOL)reKey:(NSData *)newKey {
 
 #pragma mark - set & get
 
-- (BOOL)setObject:(nullable id)object forKey:(NSString *)key {
+- (BOOL)setObject:(nullable NSObject<NSCoding> *)object forKey:(NSString *)key {
 	if (key.length <= 0) {
 		return NO;
 	}
@@ -913,12 +913,12 @@ - (BOOL)setObject:(nullable id)object forKey:(NSString *)key {
 	if ([MiniPBCoder isMiniPBCoderCompatibleObject:object]) {
 		data = [MiniPBCoder encodeDataWithObject:object];
 	} else {
-		if ([[object class] conformsToProtocol:@protocol(NSCoding)]) {
+		/*if ([object conformsToProtocol:@protocol(NSCoding)])*/ {
 			data = [NSKeyedArchiver archivedDataWithRootObject:object];
 		}
 	}
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
 }
 
 - (BOOL)setBool:(BOOL)value forKey:(NSString *)key {
@@ -930,7 +930,7 @@ - (BOOL)setBool:(BOOL)value forKey:(NSString *)key {
 	MiniCodedOutputData output(data);
 	output.writeBool(value);
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
 }
 
 - (BOOL)setInt32:(int32_t)value forKey:(NSString *)key {
@@ -942,7 +942,7 @@ - (BOOL)setInt32:(int32_t)value forKey:(NSString *)key {
 	MiniCodedOutputData output(data);
 	output.writeInt32(value);
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
 }
 
 - (BOOL)setUInt32:(uint32_t)value forKey:(NSString *)key {
@@ -954,7 +954,7 @@ - (BOOL)setUInt32:(uint32_t)value forKey:(NSString *)key {
 	MiniCodedOutputData output(data);
 	output.writeUInt32(value);
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
 }
 
 - (BOOL)setInt64:(int64_t)value forKey:(NSString *)key {
@@ -966,7 +966,7 @@ - (BOOL)setInt64:(int64_t)value forKey:(NSString *)key {
 	MiniCodedOutputData output(data);
 	output.writeInt64(value);
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
 }
 
 - (BOOL)setUInt64:(uint64_t)value forKey:(NSString *)key {
@@ -978,7 +978,7 @@ - (BOOL)setUInt64:(uint64_t)value forKey:(NSString *)key {
 	MiniCodedOutputData output(data);
 	output.writeUInt64(value);
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
 }
 
 - (BOOL)setFloat:(float)value forKey:(NSString *)key {
@@ -990,7 +990,7 @@ - (BOOL)setFloat:(float)value forKey:(NSString *)key {
 	MiniCodedOutputData output(data);
 	output.writeFloat(value);
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
 }
 
 - (BOOL)setDouble:(double)value forKey:(NSString *)key {
@@ -1002,14 +1002,26 @@ - (BOOL)setDouble:(double)value forKey:(NSString *)key {
 	MiniCodedOutputData output(data);
 	output.writeDouble(value);
 
-	return [self setData:data forKey:key];
+	return [self setRawData:data forKey:key];
+}
+
+- (BOOL)setString:(NSString *)value forKey:(NSString *)key {
+	return [self setObject:value forKey:key];
+}
+
+- (BOOL)setDate:(NSDate *)value forKey:(NSString *)key {
+	return [self setObject:value forKey:key];
+}
+
+- (BOOL)setData:(NSData *)value forKey:(NSString *)key {
+	return [self setObject:value forKey:key];
 }
 
 - (id)getObjectOfClass:(Class)cls forKey:(NSString *)key {
 	if (key.length <= 0) {
 		return nil;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 
 		if ([MiniPBCoder isMiniPBCoderCompatibleType:cls]) {
@@ -1030,7 +1042,7 @@ - (BOOL)getBoolForKey:(NSString *)key defaultValue:(BOOL)defaultValue {
 	if (key.length <= 0) {
 		return defaultValue;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 		@try {
 			MiniCodedInputData input(data);
@@ -1049,7 +1061,7 @@ - (int32_t)getInt32ForKey:(NSString *)key defaultValue:(int32_t)defaultValue {
 	if (key.length <= 0) {
 		return defaultValue;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 		@try {
 			MiniCodedInputData input(data);
@@ -1068,7 +1080,7 @@ - (uint32_t)getUInt32ForKey:(NSString *)key defaultValue:(uint32_t)defaultValue
 	if (key.length <= 0) {
 		return defaultValue;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 		@try {
 			MiniCodedInputData input(data);
@@ -1087,7 +1099,7 @@ - (int64_t)getInt64ForKey:(NSString *)key defaultValue:(int64_t)defaultValue {
 	if (key.length <= 0) {
 		return defaultValue;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 		@try {
 			MiniCodedInputData input(data);
@@ -1106,7 +1118,7 @@ - (uint64_t)getUInt64ForKey:(NSString *)key defaultValue:(uint64_t)defaultValue
 	if (key.length <= 0) {
 		return defaultValue;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 		@try {
 			MiniCodedInputData input(data);
@@ -1125,7 +1137,7 @@ - (float)getFloatForKey:(NSString *)key defaultValue:(float)defaultValue {
 	if (key.length <= 0) {
 		return defaultValue;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 		@try {
 			MiniCodedInputData input(data);
@@ -1144,7 +1156,7 @@ - (double)getDoubleForKey:(NSString *)key defaultValue:(double)defaultValue {
 	if (key.length <= 0) {
 		return defaultValue;
 	}
-	NSData *data = [self getDataForKey:key];
+	NSData *data = [self getRawDataForKey:key];
 	if (data.length > 0) {
 		@try {
 			MiniCodedInputData input(data);
@@ -1156,6 +1168,36 @@ - (double)getDoubleForKey:(NSString *)key defaultValue:(double)defaultValue {
 	return defaultValue;
 }
 
+- (nullable NSString *)getStringForKey:(NSString *)key {
+	return [self getStringForKey:key defaultValue:nil];
+}
+- (nullable NSString *)getStringForKey:(NSString *)key defaultValue:(nullable NSString *)defaultValue {
+	if (key.length <= 0) {
+		return defaultValue;
+	}
+	return [self getObjectOfClass:NSString.class forKey:key];
+}
+
+- (nullable NSDate *)getDateForKey:(NSString *)key {
+	return [self getDateForKey:key defaultValue:nil];
+}
+- (nullable NSDate *)getDateForKey:(NSString *)key defaultValue:(nullable NSDate *)defaultValue {
+	if (key.length <= 0) {
+		return defaultValue;
+	}
+	return [self getObjectOfClass:NSDate.class forKey:key];
+}
+
+- (nullable NSData *)getDataForKey:(NSString *)key {
+	return [self getDataForKey:key defaultValue:nil];
+}
+- (nullable NSData *)getDataForKey:(NSString *)key defaultValue:(nullable NSData *)defaultValue {
+	if (key.length <= 0) {
+		return defaultValue;
+	}
+	return [self getObjectOfClass:NSData.class forKey:key];
+}
+
 #pragma mark - enumerate
 
 - (BOOL)containsKey:(NSString *)key {
diff --git a/iOS/MMKV/MMKV/Resources/Info.plist b/iOS/MMKV/MMKV/Resources/Info.plist
index b84a849d..910e8276 100644
--- a/iOS/MMKV/MMKV/Resources/Info.plist
+++ b/iOS/MMKV/MMKV/Resources/Info.plist
@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>1.0.14</string>
+	<string>1.0.15</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 	<key>NSPrincipalClass</key>
diff --git a/iOS/MMKVDemo/MMKVDemo/DemoSwiftUsage.swift b/iOS/MMKVDemo/MMKVDemo/DemoSwiftUsage.swift
index 94355474..1eae2b55 100644
--- a/iOS/MMKVDemo/MMKVDemo/DemoSwiftUsage.swift
+++ b/iOS/MMKVDemo/MMKVDemo/DemoSwiftUsage.swift
@@ -48,16 +48,16 @@ class DemoSwiftUsage : NSObject {
 
         mmkv.set(Double.infinity, forKey: "double")
         print("Swift: double = \(mmkv.double(forKey: "double"))")
-
+        
         mmkv.set("Hello from Swift", forKey: "string")
-        print("Swift: string = \(mmkv.object(of: NSString.self, forKey: "string") ?? "")")
-
+        print("Swift: string = \(mmkv.string(forKey: "string") ?? "")")
+		
         mmkv.set(NSDate(), forKey: "date")
-        let date = mmkv.object(of: NSDate.self, forKey: "date") as? Date
+        let date = mmkv.date(forKey: "date")
         print("Swift: date = \(date?.description(with: .current) ?? "null")")
-
+        
         mmkv.set("Hello from Swift".data(using: .utf8) ?? Data(), forKey: "data")
-        let data = mmkv.object(of: NSData.self, forKey: "data") as? Data
+        let data = mmkv.data(forKey: "data")
         let str = String(data: data ?? Data(), encoding: .utf8) ?? ""
         print("Swift: data = \(str)")
 
diff --git a/iOS/MMKVDemo/MMKVDemo/ViewController.mm b/iOS/MMKVDemo/MMKVDemo/ViewController.mm
index 34ad6703..07d5bdc4 100644
--- a/iOS/MMKVDemo/MMKVDemo/ViewController.mm
+++ b/iOS/MMKVDemo/MMKVDemo/ViewController.mm
@@ -84,8 +84,8 @@ - (void)funcionalTest {
 	[mmkv setDouble:std::numeric_limits<double>::max() forKey:@"double"];
 	NSLog(@"double:%f", [mmkv getDoubleForKey:@"double"]);
 
-	[mmkv setObject:@"hello, mmkv" forKey:@"string"];
-	NSLog(@"string:%@", [mmkv getObjectOfClass:NSString.class forKey:@"string"]);
+	[mmkv setString:@"hello, mmkv" forKey:@"string"];
+	NSLog(@"string:%@", [mmkv getStringForKey:@"string"]);
 
 	[mmkv setObject:nil forKey:@"string"];
 	NSLog(@"string after set nil:%@, containsKey:%d",
@@ -93,11 +93,11 @@ - (void)funcionalTest {
 	                      forKey:@"string"],
 	      [mmkv containsKey:@"string"]);
 
-	[mmkv setObject:[NSDate date] forKey:@"date"];
-	NSLog(@"date:%@", [mmkv getObjectOfClass:NSDate.class forKey:@"date"]);
+	[mmkv setDate:[NSDate date] forKey:@"date"];
+	NSLog(@"date:%@", [mmkv getDateForKey:@"date"]);
 
-	[mmkv setObject:[@"hello, mmkv again and again" dataUsingEncoding:NSUTF8StringEncoding] forKey:@"data"];
-	NSData *data = [mmkv getObjectOfClass:NSData.class forKey:@"data"];
+	[mmkv setData:[@"hello, mmkv again and again" dataUsingEncoding:NSUTF8StringEncoding] forKey:@"data"];
+	NSData *data = [mmkv getDataForKey:@"data"];
 	NSLog(@"data:%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
 
 	[mmkv removeValueForKey:@"bool"];
diff --git a/iOS/MMKVDemo/MMKVDemoTests/MMKVDemoTests.mm b/iOS/MMKVDemo/MMKVDemoTests/MMKVDemoTests.mm
index 88951178..a8de46fe 100644
--- a/iOS/MMKVDemo/MMKVDemoTests/MMKVDemoTests.mm
+++ b/iOS/MMKVDemo/MMKVDemoTests/MMKVDemoTests.mm
@@ -213,6 +213,18 @@ - (void)testNSString {
 	XCTAssertEqualObjects(value, nil);
 }
 
+- (void)testNSStringForNewGetSet {
+	NSString *str = @"Hello 2018 world cup 世界杯";
+	BOOL ret = [mmkv setString:str forKey:@"string"];
+	XCTAssertEqual(ret, YES);
+
+	NSString *value = [mmkv getStringForKey:@"string"];
+	XCTAssertEqualObjects(value, str);
+
+	value = [mmkv getStringForKey:KeyNotExist];
+	XCTAssertEqualObjects(value, nil);
+}
+
 - (void)testNSData {
 	NSString *str = @"Hello 2018 world cup 世界杯";
 	NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
@@ -226,6 +238,19 @@ - (void)testNSData {
 	XCTAssertEqualObjects(value, nil);
 }
 
+- (void)testNSDataForNewGetSet {
+	NSString *str = @"Hello 2018 world cup 世界杯";
+	NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
+	BOOL ret = [mmkv setData:data forKey:@"data"];
+	XCTAssertEqual(ret, YES);
+
+	NSData *value = [mmkv getDataForKey:@"data"];
+	XCTAssertEqualObjects(value, data);
+
+	value = [mmkv getDataForKey:KeyNotExist];
+	XCTAssertEqualObjects(value, nil);
+}
+
 - (void)testNSDate {
 	NSDate *date = [NSDate date];
 	BOOL ret = [mmkv setObject:date forKey:@"date"];
@@ -238,6 +263,18 @@ - (void)testNSDate {
 	XCTAssertEqualObjects(value, nil);
 }
 
+- (void)testNSDateForNewGetSet {
+	NSDate *date = [NSDate date];
+	BOOL ret = [mmkv setDate:date forKey:@"date"];
+	XCTAssertEqual(ret, YES);
+
+	NSDate *value = [mmkv getDateForKey:@"date"];
+	XCTAssertEqualWithAccuracy(date.timeIntervalSince1970, value.timeIntervalSince1970, 0.001);
+
+	value = [mmkv getObjectOfClass:NSDate.class forKey:KeyNotExist];
+	XCTAssertEqualObjects(value, nil);
+}
+
 - (void)testNSDictionary {
 	NSDictionary *dic = @{@"key1" : @"value1",
 		                  @"key2" : @(2)};
diff --git a/iOS/MMKVDemo/MMKVMacDemo/ViewController.mm b/iOS/MMKVDemo/MMKVMacDemo/ViewController.mm
index b0e9cd13..edbc013e 100644
--- a/iOS/MMKVDemo/MMKVMacDemo/ViewController.mm
+++ b/iOS/MMKVDemo/MMKVMacDemo/ViewController.mm
@@ -62,11 +62,17 @@ - (void)funcionalTest {
 	[mmkv setDouble:std::numeric_limits<double>::max() forKey:@"double"];
 	NSLog(@"double:%f", [mmkv getDoubleForKey:@"double"]);
 
-	[mmkv setObject:@"hello, mmkv" forKey:@"string"];
-	NSLog(@"string:%@", [mmkv getObjectOfClass:NSString.class forKey:@"string"]);
+	[mmkv setString:@"hello, mmkv" forKey:@"string"];
+	NSLog(@"string:%@", [mmkv getStringForKey:@"string"]);
 
-	[mmkv setObject:[NSDate date] forKey:@"date"];
-	NSLog(@"date:%@", [mmkv getObjectOfClass:NSDate.class forKey:@"date"]);
+	//    [mmkv setObject:@"hello, mmkv" forKey:@"string"];
+	//    NSLog(@"string:%@", [mmkv getObjectOfClass:NSString.class forKey:@"string"]);
+
+	[mmkv setDate:[NSDate date] forKey:@"date"];
+	NSLog(@"date:%@", [mmkv getDateForKey:@"date"]);
+
+	//    [mmkv setObject:[NSDate date] forKey:@"date"];
+	//    NSLog(@"date:%@", [mmkv getObjectOfClass:NSDate.class forKey:@"date"]);
 
 	[mmkv setObject:[@"hello, mmkv again and again" dataUsingEncoding:NSUTF8StringEncoding] forKey:@"data"];
 	NSData *data = [mmkv getObjectOfClass:NSData.class forKey:@"data"];
diff --git a/readme_cn.md b/readme_cn.md
index 9512227a..ce77bf1a 100644
--- a/readme_cn.md
+++ b/readme_cn.md
@@ -59,8 +59,8 @@ NSString *str = [mmkv getObjectOfClass:NSString.class forKey:@"string"];
 
 ```gradle
 dependencies {
-    implementation 'com.tencent:mmkv:1.0.14'
-    // replace "1.0.14" with any available version
+    implementation 'com.tencent:mmkv:1.0.15'
+    // replace "1.0.15" with any available version
 }
 ```