WKWebView替换UIWebView

1.引入头文件

#import 

2.先使用WKWebView基本方法写个例子，加载baidu页面，写法跟UIWebView类似

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
    
    _webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 0, self.view.width, self.view.height) configuration:config];
    [self.view addSubview:_webView];
    
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.baidu.com"]];
    [_webView loadRequest:request];
}

用同样的方法，用UIWebView也写了一个页面做对比，发现差距好大，WKWebView内存是25M，而UIWebView是98M。之前没发现UIWebView内存会占如何之大，WKWebView看来很值！！！

3.监听加载的进度，因为没有“加载进度”相关的delegate回调

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self.webView addObserver:self
                   forKeyPath:@"loading"
                      options:NSKeyValueObservingOptionNew
                      context:nil];
    [self.webView addObserver:self
                   forKeyPath:@"title"
                      options:NSKeyValueObservingOptionNew
                      context:nil];
    [self.webView addObserver:self
                   forKeyPath:@"estimatedProgress"
                      options:NSKeyValueObservingOptionNew
                      context:nil];
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([keyPath isEqualToString:@"loading"]) {
        NSLog(@"loading--%d", _webView.loading);
    } else if ([keyPath isEqualToString:@"title"]) {
        NSLog(@"title--%@", _webView.title);
    } else if ([keyPath isEqualToString:@"estimatedProgress"]) {
        NSLog(@"progress--%lf", _webView.estimatedProgress);
    }
}


- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [_webView removeObserver:self forKeyPath:@"loading"];
    [_webView removeObserver:self forKeyPath:@"title"];
    [_webView removeObserver:self forKeyPath:@"estimatedProgress"];
}

记得最后移除KVO

日志如下：

2017-08-16 16:35:33.833 TestSSSSS[22084:917889] progress--0.300000
2017-08-16 16:35:33.845 TestSSSSS[22084:917889] title--百度一下
2017-08-16 16:35:34.165 TestSSSSS[22084:917889] progress--0.409694
2017-08-16 16:35:34.454 TestSSSSS[22084:917889] progress--0.845262
2017-08-16 16:35:34.472 TestSSSSS[22084:917889] progress--1.000000
2017-08-16 16:35:34.473 TestSSSSS[22084:917889] loading--0

在加载结束前取得title,最后结束时progress为1，loading为NO

4.为了方便测试，我自己写了一个html文件，页面上有个按钮，然后点击按钮弹出alert,代码如下

但是奇怪的是alert怎么也弹不出来，听说WKWebView坑很多，要慎入，现在终于碰到第一个了,
解决方法如下：

• 1.实现两个代理

_webView.UIDelegate = self;
_webView.navigationDelegate = self;

• 2.具体实现三个方法

- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler{
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"提示" message:message?:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:([UIAlertAction actionWithTitle:@"确认" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler();
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
    
}

- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler{
    //    DLOG(@"msg = %@ frmae = %@",message,frame);
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"提示" message:message?:@"" preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:([UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(NO);
    }])];
    [alertController addAction:([UIAlertAction actionWithTitle:@"确认" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(YES);
    }])];
    [self presentViewController:alertController animated:YES completion:nil];
}
- (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:@"完成" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        completionHandler(alertController.textFields[0].text?:@"");
    }])];
    
    [self presentViewController:alertController animated:YES completion:nil];
}

5.js调用oc方法 重点哦！

• js里调用方法

 window.webkit.messageHandlers.message.postMessage("hahahaha");

• oc使用方法, config里的userContentController专门处理js的调用

WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
   config.userContentController = [[WKUserContentController alloc] init];
   [config.userContentController addScriptMessageHandler:self name:@"message"];

• 接收js事件用法

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message {
  if ([message.name isEqualToString:@"message"]) {
      NSLog(@"body--%@", message.body);
      //处理js事件...
  }
}

这种写法完美的实现了js与oc的无缝连接，有点类似于服务器用的redis, 通过webKit的消息进行传递。

• remove scriptMessage, 最后要移除，千万别忘了，否则内存泄漏。

• (void)dealloc {
  [_webView.configuration.userContentController removeScriptMessageHandlerForName:@"message"];
  }

6.WKWebView加载过程代理方法：

 
 #pragma mark WKNavigationDelegate
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
    NSLog(@"start");
}

- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation {
    NSLog(@"commit");
}

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    NSLog(@"finish");
}

- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    NSLog(@"fail");
}

7.页面跳转代理方法, 可用于拦截URL

// 接收到服务器跳转请求之后调用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation {
    NSLog(@"recieve erdirect");
}

// 在收到响应后，决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler {
    decisionHandler(WKNavigationResponsePolicyAllow);
}
// 在发送请求之前，决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    decisionHandler(WKNavigationActionPolicyAllow);
}

8.OC调用JS方法

WKWebView自带的evaluateJavaScript方法

[_webView evaluateJavaScript:@"ocInvockMsg()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
            //result 是方法的返回值
            NSLog(@"result-%@", result);
        }];

WebViewJavascriptBridge第三方库 github上有9000+星，但是我觉得它适应于UIWebView，WKWebView感觉不太需要，而且WebViewJavascriptBridge需要在html添加初始化代码，侵入性太强，代码如下：

webBridge初始化及注册用于js调用oc的函数

    _bridge = [WebViewJavascriptBridge bridgeForWebView:_webView];
    [_bridge setWebViewDelegate:self];
    [WebViewJavascriptBridge enableLogging];
    [_bridge registerHandler:@"shareClick" handler:^(id data, WVJBResponseCallback responseCallback) {
        NSLog(@"share---");
    }];

oc调用js的函数，如下：

[_bridge callHandler:@"testJSFunction" data:@"aa" responseCallback:^(id responseData) {
            NSLog(@"responseData--%@", responseData);
        }];

综上所述，WebViewJavascriptBridge使用非常方便，但是前台html的业务量上升，不仅要添加初始化方法，并在刚开始时调用一次，而且还要在html里使用registerHandler和callHandler这两个方法来注册和调用方法，感觉Html里侵入性太强了，我要是做前端的我就疯了，因为它的代码还在网站上显示啊，不光是用在iOS/android上呀，而且你们iOS出了个新框架，让我前端跟着变，你当我傻？？？