diff --git a/SensorsAnalyticsSDK/SensorsAnalyticsSDK.podspec b/SensorsAnalyticsSDK/SensorsAnalyticsSDK.podspec
index 52d83c73..b48d74e9 100644
--- a/SensorsAnalyticsSDK/SensorsAnalyticsSDK.podspec
+++ b/SensorsAnalyticsSDK/SensorsAnalyticsSDK.podspec
@@ -1,137 +1,16 @@
-#
-#  Be sure to run `pod spec lint SensorsAnalyticsSDK.podspec' to ensure this is a
-#  valid spec and to remove all comments including this before submitting the spec.
-#
-#  To learn more about Podspec attributes see http://docs.cocoapods.org/specification.html
-#  To see working Podspecs in the CocoaPods repo see https://github.com/CocoaPods/Specs/
-#
-
 Pod::Spec.new do |s|
-
-  # ―――  Spec Metadata  ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  These will help people to find your library, and whilst it
-  #  can feel like a chore to fill in it's definitely to your advantage. The
-  #  summary should be tweet-length, and the description more in depth.
-  #
-
   s.name         = "SensorsAnalyticsSDK"
-  s.version      = "1.2.1"
-  s.summary      = "iOS SDK of SensorsAnalytics."
-
-  # This description is used to generate tags and improve search results.
-  #   * Think: What does it do? Why did you write it? What is the focus?
-  #   * Try to keep it short, snappy and to the point.
-  #   * Write the description between the DESC delimiters below.
-  #   * Finally, don't worry about the indent, CocoaPods strips it!
-  s.description  = <<-DESC
-                   DESC
-
+  s.version      = "1.3.1"
+  s.summary      = "The offical iOS SDK of Sensors Analytics."
   s.homepage     = "http://www.sensorsdata.cn"
-  # s.screenshots  = "www.example.com/screenshots_1.gif", "www.example.com/screenshots_2.gif"
-
-
-  # ―――  Spec License  ――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  Licensing your code is important. See http://choosealicense.com for more info.
-  #  CocoaPods will detect a license file if there is a named LICENSE*
-  #  Popular ones are 'MIT', 'BSD' and 'Apache License, Version 2.0'.
-  #
-
-  s.license      = "MIT (example)"
-  # s.license      = { :type => "MIT", :file => "FILE_LICENSE" }
-
-
-  # ――― Author Metadata  ――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  Specify the authors of the library, with email addresses. Email addresses
-  #  of the authors are extracted from the SCM log. E.g. $ git log. CocoaPods also
-  #  accepts just a name if you'd rather not provide an email address.
-  #
-  #  Specify a social_media_url where others can refer to, for example a twitter
-  #  profile URL.
-  #
-
-  s.author             = { "Yuhan ZOU" => "zouyuhan@sensorsdata.cn" }
-  # Or just: s.author    = "Yuhan ZOU"
-  # s.authors            = { "Yuhan ZOU" => "zouyuhan@sensorsdata.cn" }
-  # s.social_media_url   = "http://twitter.com/Yuhan ZOU"
-
-  # ――― Platform Specifics ――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  If this Pod runs only on iOS or OS X, then specify the platform and
-  #  the deployment target. You can optionally include the target after the platform.
-  #
-
-  s.platform     = :ios
-  s.platform     = :ios, "5.0"
-
-  #  When using multiple platforms
-  # s.ios.deployment_target = "5.0"
-  # s.osx.deployment_target = "10.7"
-  # s.watchos.deployment_target = "2.0"
-  # s.tvos.deployment_target = "9.0"
-
-
-  # ――― Source Location ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  Specify the location from where the source should be retrieved.
-  #  Supports git, hg, bzr, svn and HTTP.
-  #
-
-  s.source       = { :git => "http://EXAMPLE/SensorsAnalyticsSDK.git", :tag => "0.0.1" }
-
-
-  # ――― Source Code ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  CocoaPods is smart about how it includes source code. For source files
-  #  giving a folder will include any swift, h, m, mm, c & cpp files.
-  #  For header files it will include any header in the folder.
-  #  Not including the public_header_files will make all headers public.
-  #
-
-  s.source_files  = "Classes", "Classes/**/*.{h,m}"
-  s.exclude_files = "Classes/Exclude"
-
-  # s.public_header_files = "Classes/**/*.h"
-
-
-  # ――― Resources ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  A list of resources included with the Pod. These are copied into the
-  #  target bundle with a build phase script. Anything else will be cleaned.
-  #  You can preserve files from being cleaned, please don't preserve
-  #  non-essential files like tests, examples and documentation.
-  #
-
-  # s.resource  = "icon.png"
-  # s.resources = "Resources/*.png"
-
-  # s.preserve_paths = "FilesToSave", "MoreFilesToSave"
-
-
-  # ――― Project Linking ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  Link your library with frameworks, or libraries. Libraries do not include
-  #  the lib prefix of their name.
-  #
-
-  # s.framework  = "SomeFramework"
-  # s.frameworks = "SomeFramework", "AnotherFramework"
-
-  # s.library   = "iconv"
-  # s.libraries = "iconv", "xml2"
-
-
-  # ――― Project Settings ――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
-  #
-  #  If your library depends on compiler flags you can set them in the xcconfig hash
-  #  where they will only apply to your library. If you depend on other Podspecs
-  #  you can include multiple dependencies to ensure it works.
-
-  # s.requires_arc = true
-
-  # s.xcconfig = { "HEADER_SEARCH_PATHS" => "$(SDKROOT)/usr/include/libxml2" }
-  # s.dependency "JSONKit", "~> 1.4"
+  s.source       = { :git => 'https://github.com/sensorsdata/sa-sdk-ios.git', :tag => "v#{s.version}" } 
+  s.license = { :type => "Apache License, Version 2.0" }
+  s.author = { "Yuhan ZOU" => "zouyuhan@sensorsdata.cn" }
+
+  s.source_files  = "SensorsAnalyticsSDK/SensorsAnalyticsSDK", "SensorsAnalyticsSDK/SensorsAnalyticsSDK/*.{h,m}"
+  s.public_header_files = "SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.h"
+  s.frameworks = 'UIKit', 'Foundation', 'SystemConfiguration', 'CoreTelephony', 'CoreGraphics', 'QuartzCore'
+  s.libraries = 'icucore', 'sqlite3', 'z'
+  s.platform = :ios, "8.0"
 
 end
diff --git a/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.h b/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.h
index 6a00d03e..4954a7ac 100755
--- a/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.h
+++ b/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.h
@@ -117,7 +117,10 @@ typedef NS_ENUM(NSInteger, SensorsAnalyticsDebugMode) {
 
 /**
  * @abstract
- * 根据传入的所部署的SensorsAnalytics服务器的URL，返回一个<code>SensorsAnalyticsSDK</code>的单例
+ * 根据传入的所部署的 Sensors Analytics 服务器的URL，返回一个<code>SensorsAnalyticsSDK</code>的单例
+ *
+ * @discussion
+ * 若不需要可视化埋点功能，则 configureURL 和 vtrackServerURL 参数传入 nil 即可。
  *
  * @param serverURL 收集事件的URL
  * @param configureURL 获取配置信息的URL
diff --git a/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.m b/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.m
index af3c8b8d..646097b2 100755
--- a/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.m
+++ b/SensorsAnalyticsSDK/SensorsAnalyticsSDK/SensorsAnalyticsSDK.m
@@ -26,7 +26,7 @@
 #import "SASwizzler.h"
 #import "SensorsAnalyticsSDK.h"
 
-#define VERSION @"1.3.0"
+#define VERSION @"1.3.1"
 
 @implementation SensorsAnalyticsDebugException
 
@@ -119,20 +119,19 @@ - (instancetype)initWithServerURL:(NSString *)serverURL
                   andConfigureURL:(NSString *)configureURL
                andVTrackServerURL:(NSString *)vtrackServerURL
                      andDebugMode:(SensorsAnalyticsDebugMode)debugMode {
-    if (serverURL == nil || [serverURL length] == 0
-        || configureURL == nil || [configureURL length] == 0
-        || vtrackServerURL == nil || [vtrackServerURL length] == 0) {
+    if (serverURL == nil || [serverURL length] == 0) {
         @throw [NSException exceptionWithName:@"InvalidArgumentException"
                                        reason:@"serverURL, configureURL or vtrackServerURL is nil"
                                      userInfo:nil];
     }
     
     if (debugMode != SensorsAnalyticsDebugOff) {
-        if ([serverURL length] < [@"debug" length] || ![serverURL hasSuffix:@"debug"]) {
-            NSString *errMsg = [NSString stringWithFormat:@"The server url of SensorsAnalytics must ends with 'debug' while DEBUG mode is defined. [url='%@' expected_url='http://example.com/debug']", serverURL];
+        NSURL *serverUrl = [NSURL URLWithString:serverURL];
+        if ([serverUrl.path length] < [@"debug" length] || ![serverUrl.path hasSuffix:@"debug"]) {
+            NSString *errMsg = [NSString stringWithFormat:@"The server url of SensorsAnalytics must ends with 'debug' while DEBUG mode is defined. [url='%@' expected_url='http://example.com/debug?token=xxx']", serverURL];
             @throw [SensorsAnalyticsDebugException exceptionWithName:@"InvalidArgumentException"
-                                                                     reason:errMsg
-                                                                   userInfo:nil];
+                                                              reason:errMsg
+                                                            userInfo:nil];
         }
     }
     
@@ -191,7 +190,12 @@ - (instancetype)initWithServerURL:(NSString *)serverURL
 }
 
 - (void)flush {
-    NSArray * recordArray = [self.messageQueue getFirstRecords:50];
+    int flushSize = 50;
+    if (_debugMode != SensorsAnalyticsDebugOff) {
+        flushSize = 1;
+    }
+    
+    NSArray *recordArray = [self.messageQueue getFirstRecords:flushSize];
     if (recordArray == nil) {
         @throw [NSException exceptionWithName:@"SqliteException"
                                        reason:@"getFirstRecords from Message Queue in Sqlite fail"
@@ -219,7 +223,7 @@ - (void)flush {
         [request setHTTPBody:[postBody dataUsingEncoding:NSUTF8StringEncoding]];
         [request setValue:@"SensorsAnalytics iOS SDK" forHTTPHeaderField:@"User-Agent"];
         if (_debugMode == SensorsAnalyticsDebugOnly) {
-            [request setValue:@"true" forKey:@"Dry-Run"];
+            [request setValue:@"true" forHTTPHeaderField:@"Dry-Run"];
         }
         
         NSError *error = nil;
@@ -243,11 +247,12 @@ - (void)flush {
             NSString *urlResponseContent = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
             NSString *errMsg = [NSString stringWithFormat:@"%@ flush failure with response '%@'.", self, urlResponseContent];
             if (_debugMode != SensorsAnalyticsDebugOff) {
+                SALog(@"==========================================================================");
                 SALog(@"%@ invalid message: %@", self, jsonString);
                 SALog(@"%@ ret_code: %ld", self, [urlResponse statusCode]);
                 SALog(@"%@ ret_content: %@", self, urlResponseContent);
                 
-                @throw [SensorsAnalyticsDebugException exceptionWithName:@"NetworkException"
+                @throw [SensorsAnalyticsDebugException exceptionWithName:@"IllegalDataException"
                                                                   reason:errMsg
                                                                 userInfo:nil];
             } else {
@@ -256,16 +261,17 @@ - (void)flush {
             }
         } else {
             if (_debugMode != SensorsAnalyticsDebugOff) {
+                SALog(@"==========================================================================");
                 SALog(@"%@ valid message: %@", self, jsonString);
             }
         }
         
-        if (![self.messageQueue removeFirstRecords:50]) {
+        if (![self.messageQueue removeFirstRecords:flushSize]) {
             @throw [NSException exceptionWithName:@"SqliteException"
                                            reason:@"removeFirstRecords from Message Queue in Sqlite fail"
                                          userInfo:nil];
         }
-        recordArray = [self.messageQueue getFirstRecords:50];
+        recordArray = [self.messageQueue getFirstRecords:flushSize];
         if (recordArray == nil) {
             @throw [NSException exceptionWithName:@"SqliteException"
                                            reason:@"getFirstRecords from Message Queue in Sqlite fail"
@@ -846,6 +852,10 @@ - (void)checkForConfigure {
     dispatch_async(self.serialQueue, ^{
         SADebug(@"%@ starting configure check", self);
         
+        if (self.configureURL == nil || self.configureURL.length < 1) {
+            return;
+        }
+        
         NSURL *URL = [NSURL URLWithString:self.configureURL];
         NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
         [request setHTTPMethod:@"GET"];
@@ -896,6 +906,10 @@ - (void)connectToVTrackDesigner {
 }
 
 - (void)connectToVTrackDesigner:(BOOL)reconnect {
+    if (self.vtrackServerURL == nil || self.vtrackServerURL.length < 1) {
+        return;
+    }
+    
     if ([self.abtestDesignerConnection isKindOfClass:[SADesignerConnection class]]
             && ((SADesignerConnection *)self.abtestDesignerConnection).connected) {
         SALog(@"A/B test designer connection already exists");