UIWebView和WKWebView

其他 2019-05-03 16:30:55 阅读次数: 0

UIWebView

  • 什么是UIWebView

       UIWebView是iOS内置的浏览器控件

      系统自带的Safari浏览器就是通过UIWebView实现的

  •  UIWebView不但能加载远程的网页资源，还能加载绝大部分的常见文件

        html\htm

        pdf、doc、ppt、txt

        mp4

        … …

  •  UIWebView常用的加载资源的方法

- (void)loadRequest:(NSURLRequest *)request;

  • UIWebView控件自身存在内存泄漏的问题 

UIWebView常用属性和方法

  •   重新加载（刷新）

  • - (void)reload;

  •  停止加载

  • - (void)stopLoading;

  • 回退

  • - (void)goBack;

  • 前进

  • - (void)goForward;

  • 需要进行检测的数据类型

  • @property(nonatomic) UIDataDetectorTypes dataDetectorTypes

  • 是否能回退

  • @property(nonatomic,readonly,getter=canGoBack) BOOL canGoBack;

  • 是否能前进

  • @property(nonatomic,readonly,getter=canGoForward) BOOL canGoForward;

  • 是否正在加载中

  • @property(nonatomic,readonly,getter=isLoading) BOOL loading;

  • 是否伸缩内容至适应屏幕当前尺寸

  • @property(nonatomic) BOOL scalesPageToFit;

UIWebView常用属性和方法的代理监听

  • 成为UIWebView的代理，遵守UIWebViewDelegate协议，就能监听UIWebView的加载过程
  • 开始发送请求（加载数据）时调用这个方法

       - (void)webViewDidStartLoad:(UIWebView *)webView;

  • 请求完毕（加载数据完毕）时调用这个方法

        - (void)webViewDidFinishLoad:(UIWebView *)webView;

  • 请求错误时调用这个方法

       - (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error;

  • UIWebView在发送请求之前，都会调用这个方法，如果返回NO，代表停止加载请求，返回YES，代表允许加载请求

       - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:      (UIWebViewNavigationType)navigationType;

UIWebView的基本使用

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIWebView *webView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self test5];
}

-(void)test1
{
    NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];
    //加载网页
    [self.webView loadRequest:[NSURLRequest requestWithURL:url]];
}

-(void)test2
{
    NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];
    //加载网页
    [self.webView loadRequest:[NSURLRequest requestWithURL:url]];
    
    self.webView.scrollView.contentInset = UIEdgeInsetsMake(40, 0, 0, 0);
}

//加载本地的文件
-(void)test3
{
    NSURL *url = [NSURL fileURLWithPath:@"/Users/Alan/Desktop/NSURLSession.pptx"];
    //加载网页
    [self.webView loadRequest:[NSURLRequest requestWithURL:url]];
}

-(void)test4
{
    NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];
    //加载网页
    [self.webView loadRequest:[NSURLRequest requestWithURL:url]];
    
    //设置时候自适应
    self.webView.scalesPageToFit = YES;
}

-(void)test5
{
    NSURL *url = [[NSBundle mainBundle] URLForResource:@"text.html" withExtension:nil];
    
    //加载网页
    [self.webView loadRequest:[NSURLRequest requestWithURL:url]];
    
    //设置时候自适应
    self.webView.dataDetectorTypes = UIDataDetectorTypeAll;
}
@end

UIWebView的小用例

#import "ViewController.h"

@interface ViewController ()<UIWebViewDelegate>
@property (weak, nonatomic) IBOutlet UIWebView *webView;
@property (weak, nonatomic) IBOutlet UIBarButtonItem *goBack;
@property (weak, nonatomic) IBOutlet UIBarButtonItem *goForward;

@end

@implementation ViewController

#pragma mark ----------------------
#pragma mark Life Cycle
- (void)viewDidLoad
{
    [super viewDidLoad];
    
    NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    
    //加载网页
    [self.webView loadRequest:request];
    
    //设置代理
    self.webView.delegate = self;
}

#pragma mark ----------------------
#pragma mark Events
- (IBAction)goBackBtnClick:(id)sender
{
    
    [self.webView goBack];
}
- (IBAction)goForwardBtnClick:(id)sender
{
    [self.webView goForward];
    
}
- (IBAction)reloadBtnClick:(id)sender
{
    [self.webView reload];
}

#pragma mark ----------------------
#pragma mark UIWebViewDelegate

//即将加载某个请求的时候调用(最先调用)
-(BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
    NSLog(@"%@",request.URL.absoluteString);
    //简单的请求拦截处理
    NSString *strM = request.URL.absoluteString;
    if ([strM containsString:@"360"]) {
        return NO;
    }
    return YES;
}

//1.开始加载网页的时候调用
-(void)webViewDidStartLoad:(UIWebView *)webView
{
    NSLog(@"webViewDidStartLoad");
}

//2.加载完成的时候调用
-(void)webViewDidFinishLoad:(UIWebView *)webView
{
    NSLog(@"webViewDidFinishLoad");
    
    self.goBack.enabled = self.webView.canGoBack;
    self.goForward.enabled = self.webView.canGoForward;
}

//3.加载失败的时候调用
-(void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
{
    NSLog(@"didFailLoadWithError");
}

@end

WKWebView

一、WKWebView涉及的一些类

      1）WKWebView：网页的渲染与展示

注意： #import <WebKit/WebKit.h>
     //初始化
       _webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT) configuration:config];
        // UI代理
        _webView.UIDelegate = self;
        // 导航代理
        _webView.navigationDelegate = self;
        // 是否允许手势左滑返回上一级, 类似导航控制的左滑返回
        _webView.allowsBackForwardNavigationGestures = YES;
        //可返回的页面列表, 存储已打开过的网页 
       WKBackForwardList * backForwardList = [_webView backForwardList];

        //        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.chinadaily.com.cn"]];
        //        [request addValue:[self readCurrentCookieWithDomain:@"http://www.chinadaily.com.cn"] forHTTPHeaderField:@"Cookie"];
        //        [_webView loadRequest:request];
        //页面后退
        [_webView goBack];
        //页面前进
         [_webView goForward];
        //刷新当前页面
        [_webView reload];
        
        NSString *path = [[NSBundle mainBundle] pathForResource:@"JStoOC.html" ofType:nil];
        NSString *htmlString = [[NSString alloc]initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
      //加载本地html文件
        [_webView loadHTMLString:htmlString baseURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] bundlePath]]];

      2）WKWebViewConfiguration：为添加WKWebView配置信息

//创建网页配置对象
        WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
        
        // 创建设置对象
        WKPreferences *preference = [[WKPreferences alloc]init];
        //最小字体大小 当将javaScriptEnabled属性设置为NO时，可以看到明显的效果
        preference.minimumFontSize = 0;
        //设置是否支持javaScript 默认是支持的
        preference.javaScriptEnabled = YES;
        // 在iOS上默认为NO，表示是否允许不经过用户交互由javaScript自动打开窗口
        preference.javaScriptCanOpenWindowsAutomatically = YES;
        config.preferences = preference;
        
        // 是使用h5的视频播放器在线播放, 还是使用原生播放器全屏播放
        config.allowsInlineMediaPlayback = YES;
        //设置视频是否需要用户手动播放  设置为NO则会允许自动播放
        config.requiresUserActionForMediaPlayback = YES;
        //设置是否允许画中画技术 在特定设备上有效
        config.allowsPictureInPictureMediaPlayback = YES;
        //设置请求的User-Agent信息中应用程序名称 iOS9后可用
        config.applicationNameForUserAgent = @"ChinaDailyForiPad";
         //自定义的WKScriptMessageHandler 是为了解决内存不释放的问题
        WeakWebViewScriptMessageDelegate *weakScriptMessageDelegate = [[WeakWebViewScriptMessageDelegate alloc] initWithDelegate:self];
        //这个类主要用来做native与JavaScript的交互管理
        WKUserContentController * wkUController = [[WKUserContentController alloc] init];
        //注册一个name为jsToOcNoPrams的js方法
        [wkUController addScriptMessageHandler:weakScriptMessageDelegate  name:@"jsToOcNoPrams"];
        [wkUController addScriptMessageHandler:weakScriptMessageDelegate  name:@"jsToOcWithPrams"]; 
       config.userContentController = wkUController;

        3）WKUserScript：用于进行JavaScript注入

   //以下代码适配文本大小，由UIWebView换为WKWebView后，会发现字体小了很多，这应该是WKWebView与html的兼容问题，解决办法是修改原网页，要么我们手动注入JS
        NSString *jSString = @"var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);";
        //用于进行JavaScript注入
        WKUserScript *wkUScript = [[WKUserScript alloc] initWithSource:jSString injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
        [config.userContentController addUserScript:wkUScript];

        4）WKUserContentController：这个类主要用来做native与JavaScript的交互管理

//这个类主要用来做native与JavaScript的交互管理
        WKUserContentController * wkUController = [[WKUserContentController alloc] init];
        //注册一个name为jsToOcNoPrams的js方法，设置处理接收JS方法的代理
        [wkUController addScriptMessageHandler:self  name:@"jsToOcNoPrams"];
        [wkUController addScriptMessageHandler:self  name:@"jsToOcWithPrams"];
        config.userContentController = wkUController;
       //用完记得移除
       //移除注册的js方法
        [[_webView configuration].userContentController removeScriptMessageHandlerForName:@"jsToOcNoPrams"];
       [[_webView configuration].userContentController removeScriptMessageHandlerForName:@"jsToOcWithPrams"];

        5）WKScriptMessageHandler：这个协议类专门用来处理监听JavaScript方法从而调用原生OC方法，和WKUserContentController搭配使用

注意：遵守WKScriptMessageHandler协议，代理是由WKUserContentControl设置

   //通过接收JS传出消息的name进行捕捉的回调方法
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);
    //用message.body获得JS传出的参数体
    NSDictionary * parameter = message.body;
    //JS调用OC
    if([message.name isEqualToString:@"jsToOcNoPrams"]){
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"js调用到了oc" message:@"不带参数" preferredStyle:UIAlertControllerStyleAlert];
        [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        }])];
        [self presentViewController:alertController animated:YES completion:nil];
        
    }else if([message.name isEqualToString:@"jsToOcWithPrams"]){
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"js调用到了oc" message:parameter[@"params"] preferredStyle:UIAlertControllerStyleAlert];
        [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        }])];
        [self presentViewController:alertController animated:YES completion:nil];
    }
}

WKWebView涉及的代理方法

     1）WKNavigationDelegate ：主要处理一些跳转、加载处理操作

    // 页面开始加载时调用
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
}
    // 页面加载失败时调用
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(null_unspecified WKNavigation *)navigation withError:(NSError *)error {
    [self.progressView setProgress:0.0f animated:NO];
} 
    // 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 {
    [self getCookie];
}
    //提交发生错误时调用
- (void)webView:(WKWebView *)webView didFailNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    [self.progressView setProgress:0.0f animated:NO];
}  
   // 接收到服务器跳转请求即服务重定向时之后调用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation {
}
    // 根据WebView对于即将跳转的HTTP请求头信息和相关信息来决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    
    NSString * urlStr = navigationAction.request.URL.absoluteString;
    NSLog(@"发送跳转请求：%@",urlStr);
    //自己定义的协议头
    NSString *htmlHeadString = @"github://";
    if([urlStr hasPrefix:htmlHeadString]){
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"通过截取URL调用OC" message:@"你想前往我的Github主页?" preferredStyle:UIAlertControllerStyleAlert];
        [alertController addAction:([UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {   
        }])];
        [alertController addAction:([UIAlertAction actionWithTitle:@"打开" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
            NSURL * url = [NSURL URLWithString:[urlStr stringByReplacingOccurrencesOfString:@"github://callName_?" withString:@""]];
            [[UIApplication sharedApplication] openURL:url];
        }])];
        [self presentViewController:alertController animated:YES completion:nil];
        decisionHandler(WKNavigationActionPolicyCancel);
    }else{
        decisionHandler(WKNavigationActionPolicyAllow);
    }
}
    
    // 根据客户端受到的服务器响应头以及response相关信息来决定是否可以跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{
    NSString * urlStr = navigationResponse.response.URL.absoluteString;
    NSLog(@"当前跳转地址：%@",urlStr);
    //允许跳转
    decisionHandler(WKNavigationResponsePolicyAllow);
    //不允许跳转
    //decisionHandler(WKNavigationResponsePolicyCancel);
} 
    //需要响应身份验证时调用 同样在block中需要传入用户身份凭证
- (void)webView:(WKWebView *)webView didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable credential))completionHandler{
    //用户身份信息
    NSURLCredential * newCred = [[NSURLCredential alloc] initWithUser:@"user123" password:@"123" persistence:NSURLCredentialPersistenceNone];
    //为 challenge 的发送方提供 credential
    [challenge.sender useCredential:newCred forAuthenticationChallenge:challenge];
    completionHandler(NSURLSessionAuthChallengeUseCredential,newCred);
}
    //进程被终止时调用
- (void)webViewWebContentProcessDidTerminate:(WKWebView *)webView{
}

     2）WKNavigationDelegate ：主要处理一些跳转、加载处理操作

// 页面开始加载时调用
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
}
    // 页面加载失败时调用
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(null_unspecified WKNavigation *)navigation withError:(NSError *)error {
    [self.progressView setProgress:0.0f animated:NO];
} 
    // 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 {
    [self getCookie];
}
    //提交发生错误时调用
- (void)webView:(WKWebView *)webView didFailNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    [self.progressView setProgress:0.0f animated:NO];
}  
   // 接收到服务器跳转请求即服务重定向时之后调用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation {
}
    // 根据WebView对于即将跳转的HTTP请求头信息和相关信息来决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    
    NSString * urlStr = navigationAction.request.URL.absoluteString;
    NSLog(@"发送跳转请求：%@",urlStr);
    //自己定义的协议头
    NSString *htmlHeadString = @"github://";
    if([urlStr hasPrefix:htmlHeadString]){
        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"通过截取URL调用OC" message:@"你想前往我的Github主页?" preferredStyle:UIAlertControllerStyleAlert];
        [alertController addAction:([UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {   
        }])];
        [alertController addAction:([UIAlertAction actionWithTitle:@"打开" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
            NSURL * url = [NSURL URLWithString:[urlStr stringByReplacingOccurrencesOfString:@"github://callName_?" withString:@""]];
            [[UIApplication sharedApplication] openURL:url];
        }])];
        [self presentViewController:alertController animated:YES completion:nil];
        decisionHandler(WKNavigationActionPolicyCancel);
    }else{
        decisionHandler(WKNavigationActionPolicyAllow);
    }
}
    
    // 根据客户端受到的服务器响应头以及response相关信息来决定是否可以跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{
    NSString * urlStr = navigationResponse.response.URL.absoluteString;
    NSLog(@"当前跳转地址：%@",urlStr);
    //允许跳转
    decisionHandler(WKNavigationResponsePolicyAllow);
    //不允许跳转
    //decisionHandler(WKNavigationResponsePolicyCancel);
} 
    //需要响应身份验证时调用 同样在block中需要传入用户身份凭证
- (void)webView:(WKWebView *)webView didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable credential))completionHandler{
    //用户身份信息
    NSURLCredential * newCred = [[NSURLCredential alloc] initWithUser:@"user123" password:@"123" persistence:NSURLCredentialPersistenceNone];
    //为 challenge 的发送方提供 credential
    [challenge.sender useCredential:newCred forAuthenticationChallenge:challenge];
    completionHandler(NSURLSessionAuthChallengeUseCredential,newCred);
}
    //进程被终止时调用
- (void)webViewWebContentProcessDidTerminate:(WKWebView *)webView{
}

     3）WKUIDelegate ：主要处理JS脚本，确认框，警告框等

/**
     *  web界面中有弹出警告框时调用
     *
     *  @param webView           实现该代理的webview
     *  @param message           警告框中的内容
     *  @param completionHandler 警告框消失调用
     */
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler {
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"HTML的弹出框" message:message?:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler();
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
}
    // 确认框
    //JavaScript调用confirm方法后回调的方法 confirm是js中的确定框，需要在block中把用户选择的情况传递进去
- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler{
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"" message:message?:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:([UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(NO);
    }])];
    [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(YES);
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
}
    // 输入框
    //JavaScript调用prompt方法后回调的方法 prompt是js中的输入框 需要在block中把用户输入的信息传入
- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * _Nullable))completionHandler{
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:prompt message:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
        textField.text = defaultText;
    }];
    [alertController addAction:([UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(alertController.textFields[0].text?:@"");
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
}
    // 页面是弹出窗口 _blank 处理
- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures {
    if (!navigationAction.targetFrame.isMainFrame) {
        [webView loadRequest:navigationAction.request];
    }
    return nil;
}

WKWebView网页内容加载进度条和title的实现

//添加监测网页加载进度的观察者
    [self.webView addObserver:self
                   forKeyPath:@"estimatedProgress"
                      options:0
                      context:nil];
   //添加监测网页标题title的观察者
    [self.webView addObserver:self
                   forKeyPath:@"title"
                      options:NSKeyValueObservingOptionNew
                      context:nil];

   //kvo 监听进度 必须实现此方法
-(void)observeValueForKeyPath:(NSString *)keyPath
                     ofObject:(id)object
                       change:(NSDictionary<NSKeyValueChangeKey,id> *)change
                      context:(void *)context{
    if ([keyPath isEqualToString:NSStringFromSelector(@selector(estimatedProgress))]
        && object == _webView) {
       NSLog(@"网页加载进度 = %f",_webView.estimatedProgress);
        self.progressView.progress = _webView.estimatedProgress;
        if (_webView.estimatedProgress >= 1.0f) {
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
                self.progressView.progress = 0;
            });
        } 
    }else if([keyPath isEqualToString:@"title"]
             && object == _webView){
        self.navigationItem.title = _webView.title;
    }else{
        [super observeValueForKeyPath:keyPath
                             ofObject:object
                               change:change
                              context:context];
    }
}
    //移除观察者
    [_webView removeObserver:self
                  forKeyPath:NSStringFromSelector(@selector(estimatedProgress))];
    [_webView removeObserver:self
                  forKeyPath:NSStringFromSelector(@selector(title))];

WKWebView的JS和OC的交互

这个实现主要是依靠WKScriptMessageHandler协议类和WKUserContentController两个类：WKUserContentController对象负责注册JS方法，设置处理接收JS方法的代理，代理遵守WKScriptMessageHandler，实现捕捉到JS消息的回调方法，详情可以看第一步中对这两个类的介绍。

 1）JS调用OC

 //这个类主要用来做native与JavaScript的交互管理
        WKUserContentController * wkUController = [[WKUserContentController alloc] init];
        //注册一个name为jsToOcNoPrams的js方法，设置处理接收JS方法的代理
        [wkUController addScriptMessageHandler:self  name:@"jsToOcNoPrams"];
        [wkUController addScriptMessageHandler:self  name:@"jsToOcWithPrams"];
        config.userContentController = wkUController;

注意：遵守WKScriptMessageHandler协议，代理是由WKUserContentControl设置
 //通过接收JS传出消息的name进行捕捉的回调方法  js调OC
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);
}

2）OC调用JS

//OC调用JS  changeColor()是JS方法名，completionHandler是异步回调block
    NSString *jsString = [NSString stringWithFormat:@"changeColor('%@')", @"Js参数"];
    [_webView evaluateJavaScript:jsString completionHandler:^(id _Nullable data, NSError * _Nullable error) {
        NSLog(@"改变HTML的背景色");
    }];
    
    //改变字体大小 调用原生JS方法
    NSString *jsFont = [NSString stringWithFormat:@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '%d%%'", arc4random()%99 + 100];
    [_webView evaluateJavaScript:jsFont completionHandler:nil];

参考：https://www.jianshu.com/p/5cf0d241ae12

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