OC写法:     swift写法再下下面。

 清除WKWebView的缓存，让H5页面一刷新就更新至最新的页面

 要区分iOS9.0和8.0两种

 - (void)deleteWebCache {

     if ([[UIDevice currentDevice].systemVersion floatValue] >= 9.0) {

         NSSet *websiteDataTypes

         = [NSSet setWithArray:@[

                                 WKWebsiteDataTypeDiskCache,

                                 //WKWebsiteDataTypeOfflineWebApplicationCache,

                                 WKWebsiteDataTypeMemoryCache,

                                 //WKWebsiteDataTypeLocalStorage,

                                 //WKWebsiteDataTypeCookies,

                                 //WKWebsiteDataTypeSessionStorage,

                                 //WKWebsiteDataTypeIndexedDBDatabases,

                                 //WKWebsiteDataTypeWebSQLDatabases

                                 ]];

         //// All kinds of data

         //NSSet *websiteDataTypes = [WKWebsiteDataStore allWebsiteDataTypes];

         //// Date from

         NSDate *dateFrom = [NSDate dateWithTimeIntervalSince1970:];

         //// Execute

         [[WKWebsiteDataStore defaultDataStore] removeDataOfTypes:websiteDataTypes modifiedSince:dateFrom completionHandler:^{

             // Done

         }];

     } else {

         NSString *libraryPath = [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) objectAtIndex:];

         NSString *cookiesFolderPath = [libraryPath stringByAppendingString:@"/Cookies"];

         NSError *errors;

         [[NSFileManager defaultManager] removeItemAtPath:cookiesFolderPath error:&errors];

     }

 }

 swift:

 // MARK: - 清空缓存

     func ClearCache() {

         let dateFrom: NSDate = NSDate.init(timeIntervalSince1970: )

         if #available(iOS 9.0, *) {

             let websiteDataTypes: NSSet = WKWebsiteDataStore.allWebsiteDataTypes()

             WKWebsiteDataStore.defaultDataStore().removeDataOfTypes(websiteDataTypes as! Set<String>, modifiedSince: dateFrom) {

                 print("清空缓存完成")

             }

         } else {

               let libraryPath = NSSearchPathForDirectoriesInDomains(.LibraryDirectory, .UserDomainMask, true)[]

             let cookiesFolderPath = libraryPath.stringByAppendingString("/Cookies")

             let errors: NSError

             try? NSFileManager.defaultManager().removeItemAtPath(cookiesFolderPath)

         }

     }