发送图片是清晰的，接受到的图片是模糊的

/*!
 @Method
 @brief 以NSData构造图片对象
 @discussion
 @param aData 图片内容
 @param aDisplayName 图片对象的显示名
 @result 图片对象
 */
- (id)initWithData:(NSData *)aData displayName:(NSString *)aDisplayName;
用这种方法构造图片
环信demo中，在EaseSDKHelper.m类（3.0的UI）,+ (EMMessage *)sendImageMessageWithImage:(UIImage *)image
                                      to:(NSString *)to
                             messageType:(EMMessageType)messageType
                       requireEncryption:(BOOL)requireEncryption
                              messageExt:(NSDictionary *)messageExt
                                 quality:(float)quality
                                progress:(id<IEMChatProgressDelegate>)progress方法中
    EMChatImage *chatImage = [[EMChatImage alloc] initWithData:UIImageJPEGRepresent ation(image,1.0) displayName:@"image.jpg"];用这种方法构造

 

发送原图，大多数情况下不需要吧