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

1 - (void)viewDidLoad 
2 {
3     [super viewDidLoad];
4     webView = [[WKWebView alloc] initWithFrame:self.view.frame];
5     [self.view addSubview:webView];
6     webView.UIDelegate = self;
7     webView.navigationDelegate = self;
8     [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];
9 }

2、WKUIDelegate中的代理方法

 1 #pragma mark - WKUIDelegate
 2 // 创建一个新的WebView
 3 - (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures{
 4     return [[WKWebView alloc]init];
 5 }
 6 
 7 // 输入框
 8 - (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(nullable NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * __nullable result))completionHandler{
 9     completionHandler(@"http");
10 }
11 
12 // 确认框
13 - (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL result))completionHandler{
14     completionHandler(YES);
15 }
16 
17 // 警告框
18 - (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler{
19     NSLog(@"%@",message);
20     completionHandler();
21 }

3、WKNavigationDelegate中的代理方法

 1 #pragma mark - WKNavigationDelegate
 2 // 页面开始加载时调用
 3 - (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation{
 4     
 5 }
 6 
 7 // 当内容开始返回时调用
 8 - (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation{
 9     
10 }
11 
12 // 页面加载完成之后调用
13 - (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation{
14     
15 }
16 
17 // 页面加载失败时调用
18 - (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation{
19     
20 }
21 
22 // 接收到服务器跳转请求之后调用
23 - (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation{
24     
25 }
26 
27 // 在收到响应后，决定是否跳转
28 - (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{
29    NSLog(@"%@",navigationResponse.response.URL.absoluteString);
30     //允许跳转
31     decisionHandler(WKNavigationResponsePolicyAllow);
32     //不允许跳转
33     //decisionHandler(WKNavigationResponsePolicyCancel);
34 }
35 
36 // 在发送请求之前，决定是否跳转
37 - (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler{
38     NSLog(@"%@",navigationAction.request.URL.absoluteString);
39     //允许跳转
40     decisionHandler(WKNavigationActionPolicyAllow);
41     //不允许跳转
42     //decisionHandler(WKNavigationActionPolicyCancel);
43 }

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

 1 @interface ViewController ()<WKUIDelegate,WKNavigationDelegate,WKScriptMessageHandler>{
 2     WKWebView * webView;
 3     WKUserContentController* userContentController;
 4 }
 5 @end
 6 @implementation ViewController
 7
 8 - (void)viewDidLoad {
 9     [super viewDidLoad];
10     //配置环境
11     WKWebViewConfiguration * configuration = [[WKWebViewConfiguration alloc]init];
12     userContentController =[[WKUserContentController alloc]init];
13     configuration.userContentController = userContentController;
14     webView = [[WKWebView alloc]initWithFrame:self.view.frame configuration:configuration];
15     //注册方法
16     [userContentController addScriptMessageHandler:self  name:@"sayhello"];//注册一个name为sayhello的js方法
17 
18     [self.view addSubview:webView];
19      webView.UIDelegate = self;
20     webView.navigationDelegate = self;
21     [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];
22 }
23 - (void)dealloc{
24     //这里需要注意，前面增加过的方法一定要remove掉。
25     [userContentController removeScriptMessageHandlerForName:@"sayhello"];
26 }
27 #pragma mark - WKScriptMessageHandler
28 - (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
29     NSLog(@"name:%@\\n body:%@\\n frameInfo:%@\\n",message.name,message.body,message.frameInfo);
30 }
31 @end

2、WKDelegateController.h代码：

 1 #import <UIKit/UIKit.h>
 2 #import <WebKit/WebKit.h>
 3 @protocol WKDelegate <NSObject>
 4 
 5 - (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message;
 6 
 7 @end
 8 
 9 @interface WKDelegateController : UIViewController <WKScriptMessageHandler>
10 
11 @property (weak , nonatomic) id<WKDelegate> delegate;
12 @end

3、WKDelegateController.m代码：

 1 #import "WKDelegateController.h"
 2 
 3 @interface WKDelegateController ()
 4 
 5 @end
 6 
 7 @implementation WKDelegateController
 8 
 9 - (void)viewDidLoad {
10     [super viewDidLoad];
11 }
12 
13 - (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
14     if ([self.delegate respondsToSelector:@selector(userContentController:didReceiveScriptMessage:)]) {
15         [self.delegate userContentController:userContentController didReceiveScriptMessage:message];
16     }
17 }
18 
19 
20 @end

H5代码：

 1 <html>
 2 <head>
 3     <script>
 4 function say()
 5 {
 6 //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
 7     window.webkit.messageHandlers.sayhello.postMessage({body: 'hello world!'});
 8 }
 9 </script>
10 </head>
11     <body>
12         <h1>hello world</h1>
13         <button onclick="say()">say hello</button>
14     </body>
15 
16 </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

1 - (void)webView:(WKWebView *)tmpWebView didFinishNavigation:(WKNavigation *)navigation{
2 
3     //say()是JS方法名，completionHandler是异步回调block
4     [webView evaluateJavaScript:@"say()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
5         NSLog(@"%@",result);
6     }];
7 
8 }

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：

 1 //初始化方法
 2 + (instancetype)bridgeForWebView:(WKWebView*)webView;
 3 
 4 + (void)enableLogging;
 5 
 6 //注册函数名
 7 - (void)registerHandler:(NSString*)handlerName handler:(WVJBHandler)handler;
 8 
 9 //调用函数名
10 - (void)callHandler:(NSString*)handlerName; 
11 - (void)callHandler:(NSString*)handlerName data:(id)data; 
12 - (void)callHandler:(NSString*)handlerName data:(id)data responseCallback:(WVJBResponseCallback)responseCallback;
13 
14 //重置
15 - (void)reset;
16 
17 //设置WKNavigationDelegate
18 - (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。