diff --git a/VVRichText.podspec b/VVRichText.podspec
index 5d8a6d8..4b56fe5 100644
--- a/VVRichText.podspec
+++ b/VVRichText.podspec
@@ -6,8 +6,10 @@ Pod::Spec.new do |spec|
   spec.homepage     = "https://github.com/chinaxxren/VVRichText"
   spec.license      = "MIT"
   spec.author       = { "chinaxxren" => "182421693@qq.com" }
-  spec.platform     = :ios, "8.0"
-  spec.source       = { :git => "https://github.com/chinaxxren/VVRichText", :tag => "#{spec.version}" }
+  spec.platform     = :ios, "9.0"
+  spec.source       = { :git => "https://github.com/chinaxxren/VVRichText.git", :tag => "#{spec.version}" }
   spec.source_files  = "VVRichText/Source", "VVRichText/Source/**/*.{h,m}"
-  spec.frameworks = "YYImage/WebP", "SDWebImage"
+  spec.frameworks  = "UIKit"
+  spec.dependency  "YYImage/WebP"
+  spec.dependency  "SDWebImage"
 end
diff --git a/VVRichText/Source/VVLayout.h b/VVRichText/Source/VVLayout.h
index 7521f86..46bbee8 100755
--- a/VVRichText/Source/VVLayout.h
+++ b/VVRichText/Source/VVLayout.h
@@ -12,28 +12,28 @@
  *
  *  @param storage 一个VVStorage对象
  */
-- (void)addStorage:(VVStorage *)storage;
+- (void)addStorage:(nullable VVStorage *)storage;
 
 /**
  *  添加一个包含VVStorage对象的数组的所有元素到VVLayout
  *
  *  @param storages 一个包含VVStorage对象的数组
  */
-- (void)addStorages:(NSArray <VVStorage *> *)storages;
+- (void)addStorages:(nullable NSArray <VVStorage *> *)storages;
 
 /**
  *  移除一个VVStorage对象
  *
  *  @param storage 一个VVStorage对象
  */
-- (void)removeStorage:(VVStorage *)storage;
+- (void)removeStorage:(nullable VVStorage *)storage;
 
 /**
  *  移除一个包含VVStorage对象的数组的所有元素
  *
  *  @param storages 一个包含VVStorage对象的数组
  */
-- (void)removeStorages:(NSArray <VVStorage *> *)storages;
+- (void)removeStorages:(nullable NSArray <VVStorage *> *)storages;
 
 /**
  *  获取到一个建议的高度，主要用于UITabelViewCell的高度设定。
@@ -49,18 +49,18 @@
 /**
  *  获取包含VVTextStorage的数组
  */
-- (NSMutableArray<VVTextStorage *> *)textStorages;
+- (nullable NSMutableArray<VVTextStorage *> *)textStorages;
 
 /**
  *  获取包含VVImageStorage的数组
  */
-- (NSMutableArray<VVImageStorage *> *)imageStorages;
+- (nullable NSMutableArray<VVImageStorage *> *)imageStorages;
 
 
 /**
  *  获取包含所有的VVStorage的数组
  */
-- (NSMutableArray<VVStorage *> *)totalStorages;
+- (nullable NSMutableArray<VVStorage *> *)totalStorages;
 
 
 @end
diff --git a/VVRichText/Source/VVLayout.m b/VVRichText/Source/VVLayout.m
index 89f9e26..d0f705e 100755
--- a/VVRichText/Source/VVLayout.m
+++ b/VVRichText/Source/VVLayout.m
@@ -54,7 +54,7 @@ - (id)initWithCoder:(NSCoder *)aDecoder {
     return self;
 }
 
-- (void)addStorage:(VVStorage *)storage {
+- (void)addStorage:(nullable VVStorage *)storage {
     if (!storage) {
         return;
     }
@@ -70,7 +70,7 @@ - (void)addStorage:(VVStorage *)storage {
     [self.totalStorages addObject:storage];
 }
 
-- (void)addStorages:(NSArray <VVStorage *> *)storages {
+- (void)addStorages:(nullable NSArray <VVStorage *> *)storages {
     if (!storages) {
         return;
     }
@@ -83,7 +83,7 @@ - (void)addStorages:(NSArray <VVStorage *> *)storages {
 }
 
 
-- (void)removeStorage:(VVStorage *)storage {
+- (void)removeStorage:(nullable VVStorage *)storage {
     if (!storage) {
         return;
     }
@@ -101,7 +101,7 @@ - (void)removeStorage:(VVStorage *)storage {
     }
 }
 
-- (void)removeStorages:(NSArray <VVStorage *> *)storages {
+- (void)removeStorages:(nullable NSArray <VVStorage *> *)storages {
     if (!storages) {
         return;
     }
@@ -122,7 +122,7 @@ - (CGFloat)suggestHeightWithBottomMargin:(CGFloat)bottomMargin {
 
 #pragma mark - Getter
 
-- (NSMutableArray *)textStorages {
+- (nullable NSMutableArray *)textStorages {
     if (_textStorages) {
         return _textStorages;
     }
@@ -130,7 +130,7 @@ - (NSMutableArray *)textStorages {
     return _textStorages;
 }
 
-- (NSMutableArray *)imageStorages {
+- (nullable NSMutableArray *)imageStorages {
     if (_imageStorages) {
         return _imageStorages;
     }
@@ -138,7 +138,7 @@ - (NSMutableArray *)imageStorages {
     return _imageStorages;
 }
 
-- (NSMutableArray *)totalStorages {
+- (nullable NSMutableArray *)totalStorages {
     if (_totalStorages) {
         return _totalStorages;
     }
diff --git a/VVRichText/Source/VVStorage.h b/VVRichText/Source/VVStorage.h
index 4ef0637..77a514d 100755
--- a/VVRichText/Source/VVStorage.h
+++ b/VVRichText/Source/VVStorage.h
@@ -7,7 +7,7 @@
  */
 @interface VVStorage : NSObject
 
-@property(nullable, nonatomic, copy) NSString *identifier;//一个标示字符串，可以用于复用时取到属性相同的UIView对象
+@property(nonatomic, copy, nonnull) NSString *identifier;//一个标示字符串，可以用于复用时取到属性相同的UIView对象
 @property(nonatomic, assign) NSInteger tag;//一个标示符，跟UIView对象的tag属性作用一样
 @property(nonatomic, assign) BOOL clipsToBounds;//是否在边缘剪切，跟UIView对象的clipsToBounds属性作用一样
 @property(nonatomic, getter = isOpaque) BOOL opaque;//跟UIView对象的同名属性作用一样
diff --git a/VVRichText/Source/VVStorage.m b/VVRichText/Source/VVStorage.m
index 3fe7109..28e77b0 100755
--- a/VVRichText/Source/VVStorage.m
+++ b/VVRichText/Source/VVStorage.m
@@ -20,7 +20,7 @@ @implementation VVStorage
 
 #pragma mark - Init
 
-- (id)initWithIdentifier:(NSString *)identifier {
+- (_Nonnull id)initWithIdentifier:(NSString *_Nullable)identifier {
     self = [super init];
     if (self) {
         self.identifier = identifier;
diff --git a/VVRichText/Source/WebCache/VVAsyncImageView+WebCache.h b/VVRichText/Source/WebCache/VVAsyncImageView+WebCache.h
index c266453..4341abf 100755
--- a/VVRichText/Source/WebCache/VVAsyncImageView+WebCache.h
+++ b/VVRichText/Source/WebCache/VVAsyncImageView+WebCache.h
@@ -6,11 +6,7 @@
 
 /**
  *  设置VVAsyncImageView的图片内容
- *  @param imageStorage          VVImageStorage对象
- *  @param placeholder           这个block用于VVHTMLDisplayView渲染时，自动调整图片的比例
- *  @param cornerRadius          这个block图像显示完毕后回调
  */
-
 - (void)vv_setImageWihtImageStorage:(VVImageStorage *)imageStorage
                              resize:(VVHTMLImageResizeBlock)resizeBlock
                          completion:(VVAsyncCompleteBlock)completion;
diff --git a/VVRichText/Source/WebCache/YYAnimatedImageView+WebCache.h b/VVRichText/Source/WebCache/YYAnimatedImageView+WebCache.h
index 6b851ec..32c4d36 100644
--- a/VVRichText/Source/WebCache/YYAnimatedImageView+WebCache.h
+++ b/VVRichText/Source/WebCache/YYAnimatedImageView+WebCache.h
@@ -29,12 +29,12 @@ typedef void(^SDSetImageBlock)(UIImage *_Nullable image, NSData *_Nullable image
 
 - (void)sd_setImageWithURL:(nullable NSURL *)url
           placeholderImage:(nullable UIImage *)placeholder
-              imageStorage:(VVImageStorage *)imageStorage
+              imageStorage:(nullable VVImageStorage *)imageStorage
                  completed:(nullable SDExternalCompletionBlock)completedBlock;
 
 - (void)sd_internalSetImageWithURL:(nullable NSURL *)url
                   placeholderImage:(nullable UIImage *)placeholder
-                      imageStorage:(VVImageStorage *)imageStorage
+                      imageStorage:(nullable VVImageStorage *)imageStorage
                            options:(SDWebImageOptions)options
                            context:(nullable SDWebImageContext *)context
                      setImageBlock:(nullable SDSetImageBlock)setImageBlock