IOS进阶之WKWebView

前言

Xcode8发布以后，编译器开始不支持IOS7，所以很多应用在适配IOS10之后都不在适配IOS7了，其中包括了很多大公司，网易新闻，滴滴出行等。因此，我们公司的应用也打算淘汰IOS7。

支持到IOS8，第一个要改的自然是用WKWebView替换原来的UIWebView。WKWebView有很多明显优势:

更多的支持HTML5的特性
官方宣称的高达60fps的滚动刷新率以及内置手势
将UIWebViewDelegate与UIWebView拆分成了14类与3个协议,以前很多不方便实现的功能得以实现。文档
Safari相同的JavaScript引擎
占用更少的内存

UIWebView

WKWebView

因此，使用WKWebView替换UIWebView还是很有必要的。

基本使用方法

WKWebView有两个delegate,WKUIDelegate 和 WKNavigationDelegate。WKNavigationDelegate主要处理一些跳转、加载处理操作，WKUIDelegate主要处理JS脚本，确认框，警告框等。因此WKNavigationDelegate更加常用。

1、WKWebView的初始化

 - (void)viewDidLoad

 {

     [super viewDidLoad];

     webView = [[WKWebView alloc] initWithFrame:self.view.frame];

     [self.view addSubview:webView];

     webView.UIDelegate = self;

     webView.navigationDelegate = self;

     [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];

 }

2、WKUIDelegate中的代理方法

 #pragma mark - WKUIDelegate

 // 创建一个新的WebView

 - (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures{

     return [[WKWebView alloc]init];

 }

 // 输入框

 - (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(nullable NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * __nullable result))completionHandler{

     completionHandler(@"http");

 }

 // 确认框

 - (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL result))completionHandler{

     completionHandler(YES);

 }

 // 警告框

 - (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler{

     NSLog(@"%@",message);

     completionHandler();

 }

3、WKNavigationDelegate中的代理方法

 #pragma mark - WKNavigationDelegate

 // 页面开始加载时调用

 - (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation{

 }

 // 当内容开始返回时调用

 - (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation{

 }

 // 页面加载完成之后调用

 - (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation{

 }

 // 页面加载失败时调用

 - (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation{

 }

 // 接收到服务器跳转请求之后调用

 - (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation{

 }

 // 在收到响应后，决定是否跳转

 - (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{

    NSLog(@"%@",navigationResponse.response.URL.absoluteString);

     //允许跳转

     decisionHandler(WKNavigationResponsePolicyAllow);

     //不允许跳转

     //decisionHandler(WKNavigationResponsePolicyCancel);

 }

 // 在发送请求之前，决定是否跳转

 - (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler{

     NSLog(@"%@",navigationAction.request.URL.absoluteString);

     //允许跳转

     decisionHandler(WKNavigationActionPolicyAllow);

     //不允许跳转

     //decisionHandler(WKNavigationActionPolicyCancel);

 }

OC与JS交互

WKWebview提供了API实现js交互不需要借助JavaScriptCore或者webJavaScriptBridge。使用WKUserContentController实现js native交互。简单的说就是先注册约定好的方法，然后再调用。

1、JS调用OC方法

 @interface ViewController ()<WKUIDelegate,WKNavigationDelegate,WKScriptMessageHandler>{

     WKWebView * webView;

     WKUserContentController* userContentController;

 }

 @end

 @implementation ViewController

 - (void)viewDidLoad {

     [super viewDidLoad];

     //配置环境

     WKWebViewConfiguration * configuration = [[WKWebViewConfiguration alloc]init];

     userContentController =[[WKUserContentController alloc]init];

     configuration.userContentController = userContentController;

     webView = [[WKWebView alloc]initWithFrame:self.view.frame configuration:configuration];

     //注册方法

     [userContentController addScriptMessageHandler:self  name:@"sayhello"];//注册一个name为sayhello的js方法

     [self.view addSubview:webView];

      webView.UIDelegate = self;

     webView.navigationDelegate = self;

     [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];

 }

 - (void)dealloc{

     //这里需要注意，前面增加过的方法一定要remove掉。

     [userContentController removeScriptMessageHandlerForName:@"sayhello"];

 }

 #pragma mark - WKScriptMessageHandler

 - (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{

     NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);

 }

 @end

2、WKDelegateController.h代码：

 #import <UIKit/UIKit.h>

 #import <WebKit/WebKit.h>

 @protocol WKDelegate <NSObject>

 - (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message;

 @end

 @interface WKDelegateController : UIViewController <WKScriptMessageHandler>

 @property (weak , nonatomic) id<WKDelegate> delegate;

 @end

3、WKDelegateController.m代码：

 #import "WKDelegateController.h"

 @interface WKDelegateController ()

 @end

 @implementation WKDelegateController

 - (void)viewDidLoad {

     [super viewDidLoad];

 }

 - (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{

     if ([self.delegate respondsToSelector:@selector(userContentController:didReceiveScriptMessage:)]) {

         [self.delegate userContentController:userContentController didReceiveScriptMessage:message];

     }

 }

 @end

H5代码：

 <html>

 <head>

     <script>

 function say()

 {

 //前端需要用 window.webkit.messageHandlers.注册的方法名.postMessage({body:传输的数据} 来给native发送消息

     window.webkit.messageHandlers.sayhello.postMessage({body: 'hello world!'});

 }

 </script>

 </head>

     <body>

         <h1>hello world</h1>

         <button onclick="say()">say hello</button>

     </body>

 </html>

注意点

1、addScriptMessageHandler要和removeScriptMessageHandlerForName配套出现，否则会造成内存泄漏。

2、h5只能传一个参数，如果需要多个参数就需要用字典或者json组装。

OC调用JS方法

 - (void)webView:(WKWebView *)tmpWebView didFinishNavigation:(WKNavigation *)navigation{

     //say()是JS方法名，completionHandler是异步回调block

     [webView evaluateJavaScript:@"say()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {

         NSLog(@"%@",result);

     }];

 }

WebViewJavascriptBridge

一般来说，一个好的UI总有一个大神会开发出一个好的第三方封装框架。WebViewJavascriptBridge的作者也做了一套支持WKWebView与JS交互的第三方框架:WKWebViewJavascriptBridge。

cocoaPods: pod 'WebViewJavascriptBridge', '~> 5.0.5'

github地址：https://github.com/marcuswestin/WebViewJavascriptBridge

主要方法：

 //初始化方法

 + (instancetype)bridgeForWebView:(WKWebView*)webView;

 + (void)enableLogging;

 //注册函数名

 - (void)registerHandler:(NSString*)handlerName handler:(WVJBHandler)handler;

 //调用函数名

 - (void)callHandler:(NSString*)handlerName;

 - (void)callHandler:(NSString*)handlerName data:(id)data;

 - (void)callHandler:(NSString*)handlerName data:(id)data responseCallback:(WVJBResponseCallback)responseCallback;

 //重置

 - (void)reset;

 //设置WKNavigationDelegate

 - (void)setWebViewDelegate:(id<WKNavigationDelegate>)webViewDelegate;

基本的实现方法和上面写的差不多，就是封装了一下，有兴趣的童鞋可以自己pod下来使用。