Cookies in iOS - HTTPCookieStorage and WKHTTPCookieStore ​

There are two kinds of cookie storages in iOS app: HTTPCookieStorage and WKHTTPCookieStore.

HTTPCookieStorage ​

HTTPCookieStorage is used by apps, app extensions and UIWebViews.

By default, apps and associated app extensions will have different data containers. As a result, the value of the HTTPCookieStorage class’s shared property will refer to different persistent cookie stores when called by the app and by its extensions.

You can use the HTTPCookieStorage class’s sharedCookieStorage(forGroupContainerIdentifier:) method to create a persistent cookie storage available to all apps and extensions with access to the same app group.

UIWebView instances within an app inherit the parent app's shared cookie storage.

WKHTTPCookieStore ​

WKHTTPCookieStore is used by WKWebView.

You don’t create a WKHTTPCookieStore object directly. Instead, retrieve this object from the WKWebsiteDataStore object in your web view’s configuration object.

var httpCookeStore = self.webView.configuration.websiteDataStore.httpCookieStore

var httpCookeStore = self.webView.configuration.websiteDataStore.httpCookieStore

WKWebsiteDataStore ​

You create a WKWebViewConfiguration object in your code, configure its properties, and pass it to the initializer of your WKWebView object. The web view incorporates your configuration settings only at creation time; you cannot change those settings dynamically later.

By default, a WKWebViewConfiguration object uses the default data store returned by the default() method of WKWebsiteDataStore class, which saves website data persistently to disk.

You can also create a data store object and assign it to the websiteDataStore property of a WKWebViewConfiguration object before you create your web view.

For example:

• To create a private web-browsing session, create a nonpersistent data store using the nonPersistent() method and assign it to the websiteDataStore property.
• To implement profile browsing, create a persistent data store using the init(forIdentifier:) method, passing an identifier that you use to identify the data store.

Managing WKHTTPCookieStore ​

You can use a WKHTTPCookieStore to specify the initial cookies for your webpages, and to manage cookies for your web content. For example, you might use this object to delete the cookie for the current session when the user logs out. To detect when the webpage changes a cookie, install a cookie observer using the add(_:) method.

Cookies Sync Between HTTPCookieStorage and WKWebsiteDataStore ​

After testing on real devices, we found out iOS automatically sync cookies between HTTPCookieStorage and WKWebsiteDataStore, but with some delay of about seconds.

If your app's code relies on the cookies from WKWebView or your WKWebview relies on the cookies from the app, you may need to do your own sync logic, as the delay of iOS automatically sync will cause a lot of issues.

I wrote a demo project to test the sync delay between HTTPCookieStorage and WKWebsiteDataStore, you can check and reach out to me if has any questions.

Summary ​

References ​

• NSHTTPCookieStorage
• WKHTTPCookieStore
• WKWebViewConfiguration
• Bug 188691 - REGRESSION (iOS 12): WKWebView cookies are empty in responseHeaders
• From IOS 13.0 cookiesDidChange is never triggered when cookies change on webview