iOS下OC与JS的交互(WKWebview-MessageHandler实现)

在开发过程中，iOS 中实现加载 web 页面主要有两种控件，UIWebView和WKWebview，两种控件对应具体的实现方法不同。WKWebView是苹果公司在iOS8系统推出的，这里我们主要概述WebKit中更新的WKWebView控件的新特性与使用方法。

##一、 WKWebView的代理方法

1.WKNavigationDelegate

该代理提供的方法，可以用来追踪加载过程（页面开始加载、加载完成、加载失败）、决定是否执行跳转。

// 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;

页面跳转的代理方法有三种，分为（收到跳转与决定是否跳转两种）：

// 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;

// 在发送请求之前，决定是否跳转
-(void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler;

2.WKUIDelegate

//创建一个新的webView
-(WKWebView**)webView:(WKWebView***)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures;

下面代理方法全都是与界面弹出提示框相关的，针对于web界面的三种提示框（警告框、确认框、输入框）分别对应三种代理方法。下面只列举了警告框的方法。

-(void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(void (^)())completionHandler;

3.WKScriptMessageHandler

// 从web界面中接收到一个脚本时调用
-(void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message;

##二、WKWebView加载JS

NSString *js = @"";
// 根据JS字符串初始化WKUserScript对象
WKUserScript *script = [[WKUserScript alloc] initWithSource:js injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];

// 根据生成的WKUserScript对象，初始化WKWebViewConfiguration
WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
[config.userContentController addUserScript:script];

###下面开始进入正题

####1.首先需要引入WebKit库

 #import 

####2.MessageHandler
创建WKWebViewConfiguration，配置各个API对应的MessageHandler

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

[userContentController addScriptMessageHandler:self name:@"Share"];
[userContentController addScriptMessageHandler:self name:@"Camera"];
configuration.userContentController = userContentController;

WKPreferences *preferences = [WKPreferences new];
preferences.javaScriptCanOpenWindowsAutomatically = YES;
preferences.minimumFontSize = 40.0;
configuration.preferences = preferences;

####3.创建WKWebView

loadFileURL方法通常用于加载服务器的HTML页面或者JS，而loadHTMLString通常用于加载本地HTML或者JS

NSString *htmlPath = [[NSBundle mainBundle] pathForResource:@"WKWebViewMessageHandler" ofType:@"html"];
NSString *fileURL = [NSString stringWithContentsOfFile:htmlPath encoding:NSUTF8StringEncoding error:nil];
NSURL *baseURL = [NSURL fileURLWithPath:htmlPath];
[self.webView loadHTMLString:fileURL baseURL:baseURL];
self.webView.UIDelegate = self;
[self.view addSubview:self.webView];

####4.实现协议方法

#pragma mark -- WKScriptMessageHandler
-(void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message
{
   //JS调用OC方法
   //message.boby就是JS里传过来的参数
   NSLog(@"body:%@",message.body);

   if ([message.name isEqualToString:@"Share"]) {
   [self ShareWithInformation:message.body];

} else if ([message.name isEqualToString:@"Camera"]) {
[self camera];
}
}

WKScriptMessage有两个关键属性name 和 body。因为我们给每一个OC方法取了一个name，所以就可以根据name 来区分执行不同的方法。body 中存着JS 要给OC 传的参数。

#pragma mark - Method
-(void)ShareWithInformation:(NSDictionary *)dic
{
   if (![dic isKindOfClass:[NSDictionary class]]) {
   return;
}
   NSString *title = [dic objectForKey:@"title"];
   NSString *content = [dic objectForKey:@"content"];
   NSString *url = [dic objectForKey:@"url"];

   //在这里写分享操作的代码
   NSLog(@"要分享了哦

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