iOS has two webviews: UIWebview and WKWebview. Starting from iOS13, Apple has listed UIWebview as an expired API.The App Store will no longer accept new apps that use UIWebView from April 2020, and will no longer accept app updates that use UIWebView from December 2020.

In the development of 5+app, since HBuilderX 2.2.5, the default on iOS has been WKWebview. Unless the developer manually specifies in the code to use UIWebview, the actual rendered pages are rendered in WKWebview. However, although the actual page is rendered by WKWebview, there is still an optional reference to UIWebview in the source code of the App underlying engine. Appstore's computer review will find that the binary code includes a reference to UIWebview, which will cause an alarm.
Starting from HBuilderX 2.6.6, uiWebview has been removed from the basic engine and turned into an optional module (selected in the manifest), and the machine review is not prompted.

Now let's explain the difference between UIwebview and WKwebview and their differences.

UIwebview

UIWebView is used to embed web content in the App, usually in html format, and also supports pdf, word and other documents.

Control advantages

1. Cross-platform
   　　 It can deploy iOS, Android and other platforms once developed.

2. Fast release and update
   　　 is released on the server side, which can update the terminal display in real time, which is convenient for quick upgrades and emergency bug fixes.

3. Strong layout ability
   　　The powerful HTML+CSS makes people worship

Control disadvantages

1. performance
   　　 One of Native’s favorite sayings when arguing with HTML5 is: "Your performance is not good." Web App runs in the browser, and the open capability of the browser is difficult to support HTML5 and Native confrontation.

2. Complex data communication
   　　 Data communication between UIWebView and App can only be done through javascript or UIWebViewDelegate. It is more complicated for the client to pass parameters to UIWebView to modify the webpage or obtain data from the webpage.

scenes to be used

1. Typesetting complex content

2. Interface that needs flexible control in the background

3. Original page

WKWebview

With the application of IOS development,More and more web embedding, Before IOS 8, we used UIWebView to display the detail page. Since IOS 8, WKWebView has appeared. Compared with UIWebView, WKWebView has optimized more experience.

Advantages of WKWebView

WKWebView uses a cross-process solution, Nitro JS parser, and a refresh rate of up to 60fps. The theoretical performance is comparable to that of Safari, and it also has high support for H5.

1. The memory overhead of WKWebView is much smaller than UIWebView

2. Built-in gestures

3. Supports more HTML5 features

4. Have the same JavaScript engine as Safari

5. Provide commonly used attributes, such as estimatedProgress attribute of loading webpage progress

The difference between the two

UIWebview has existed since iOS2, and WKWebView has only existed since iOS8. There is no doubt that WKWebView will gradually replace the bulky UIWebview. Through the official performance test, it can be found that UIWebview takes up too much memory, and the peak memory is even more exaggerated. WKWebView web page loading speed has also improved, but not as much as memory.

WKWebView is a new H5 container used by Apple when it announced WebKit when it announced IOS8 at the WWDC2014 conference. Compared with UIWebView, it has faster loading speed and performance, and lower memory usage. Refactored UIWebViewDelegate and UIWebView into 14 classes and 3 protocols, allowing developers to perform more detailed configuration.

But his most fatal flaw is that the request of WKWebView cannot be intercepted by NSURLProtocol.

The above figure shows the flow of UIWebview and WKWebView. The granularity of WKWebView is more detailed. Not only will WKWebView be asked whether to request data when requesting, but also WKWebView will be asked whether to load data after returning the data.

For more information about how to use UIwebview and WKwebview, please visitTutorial link。