js与OC互相调用 —— MessageHandler

本篇文章依然是使用WKWebview来操作交互，继续认识一下WKWebview,上面文章介绍了WKWebview一些新特性，这里补充一下与之交互用到的三大代理，html文件中以及文章中会用到

WKNavigationDelegate，与页面导航加载相关
WKUIDelegate，与JS交互时的ui展示相关，比较JS的alert、confirm、prompt
WKScriptMessageHandler，与js交互相关，通常是ios端注入名称，js端通过window.webkit.messageHandlers.{NAME}.postMessage()来发消息到ios端

1.使用Html文件

html文件.png

Share  == Message name
postMessage == Message body

2.创建WKWebViewConfiguration，并且配置各个API对应的MessageHandler。

基础配置，导入框架，实现协议

#import <WebKit/WebKit.h>
@interface WKWebViewController ()<WKUIDelegate,WKScriptMessageHandler>

代码实现

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    // addScriptMessageHandler 很容易导致循环引用
    // 控制器 强引用了WKWebView,WKWebView copy(强引用了）configuration， configuration copy （强引用了）userContentController
    // userContentController 强引用了 self （控制器）
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"ScanAction"];
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Location"];
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Share"];
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Color"];
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Pay"];
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Shake"];
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"GoBack"];
    [self.webView.configuration.userContentController addScriptMessageHandler:self name:@"PlaySound"];
}
// 需要注意的是addScriptMessageHandler很容易引起循环引用，导致控制器无法被释放，所以需要加入以下这段：
- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    
    // 因此这里要记得移除handlers
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"ScanAction"];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Location"];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Share"];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Color"];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Pay"];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Shake"];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"GoBack"];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"PlaySound"];
}

3.创建WKWebView。

- (void)initWKWebView
{
    WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
    
    WKPreferences *preferences = [WKPreferences new];
    preferences.javaScriptCanOpenWindowsAutomatically = YES;
    preferences.minimumFontSize = 40.0;
    configuration.preferences = preferences;
    
    self.webView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:configuration];
 
    NSString *urlStr = [[NSBundle mainBundle] pathForResource:@"index.html" ofType:nil];
    NSURL *fileURL = [NSURL fileURLWithPath:urlStr];
    [self.webView loadFileURL:fileURL allowingReadAccessToURL:fileURL];
    
    self.webView.UIDelegate = self;
    [self.view addSubview:self.webView];
}

4.实现协议方法。

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message
{
//Share  == Message name
//postMessage == Message body
//    message.body  --  Allowed types are NSNumber, NSString, NSDate, NSArray,NSDictionary, and NSNull.
    NSLog(@"body:%@",message.body);
    if ([message.name isEqualToString:@"ScanAction"]) {
        NSLog(@"扫一扫");
    } else if ([message.name isEqualToString:@"Location"]) {
        [self getLocation];
    } else if ([message.name isEqualToString:@"Share"]) {
        [self shareWithParams:message.body];
    } else if ([message.name isEqualToString:@"Color"]) {
        [self changeBGColor:message.body];
    } else if ([message.name isEqualToString:@"Pay"]) {
        [self payWithParams:message.body];
    } else if ([message.name isEqualToString:@"Shake"]) {
        [self shakeAction];
    } else if ([message.name isEqualToString:@"GoBack"]) {
        [self goBack];
    } else if ([message.name isEqualToString:@"PlaySound"]) {
        [self playSound:message.body];
    }
}

关于WKScriptMessage的定义

@interface WKScriptMessage : NSObject

/*! @abstract The body of the message.
 @discussion Allowed types are NSNumber, NSString, NSDate, NSArray,
 NSDictionary, and NSNull.
 */
@property (nonatomic, readonly, copy) id body;

/*! @abstract The web view sending the message. */
@property (nullable, nonatomic, readonly, weak) WKWebView *webView;

/*! @abstract The frame sending the message. */
@property (nonatomic, readonly, copy) WKFrameInfo *frameInfo;

/*! @abstract The name of the message handler to which the message is sent.
 */
@property (nonatomic, readonly, copy) NSString *name;

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，那么我们就可以根据name 来区分执行不同的方法。body 中存着JS 要给OC 传的参数。

- (void)payWithParams:(NSDictionary *)tempDic
{
    if (![tempDic isKindOfClass:[NSDictionary class]]) {
        return;
    }
    NSString *orderNo = [tempDic objectForKey:@"order_no"];
    long long amount = [[tempDic objectForKey:@"amount"] longLongValue];
    NSString *subject = [tempDic objectForKey:@"subject"];
    NSString *channel = [tempDic objectForKey:@"channel"];
    NSLog(@"%@---%lld---%@---%@",orderNo,amount,subject,channel);
    
    // 支付操作
    
    // 将支付结果返回给js
    NSString *jsStr = [NSString stringWithFormat:@"payResult('%@')",@"支付成功"];
    [self.webView evaluateJavaScript:jsStr completionHandler:^(id _Nullable result, NSError * _Nullable error) {
        NSLog(@"%@----%@",result, error);
    }];
}

5.处理HTML中JS调用。

// 见文章开头图片文件
 function scanClick() {
                window.webkit.messageHandlers.ScanAction.postMessage(null);
            }
                
            function shareClick() {
                window.webkit.messageHandlers.Share.postMessage({title:'测试分享的标题',content:'测试分享的内容',url:'http://m.rblcmall.com/share/openShare.htm?share_uuid=shdfxdfdsfsdfs&share_url=http://m.rblcmall.com/store_index_32787.htm&imagePath=http://c.hiphotos.baidu.com/image/pic/item/f3d3572c11dfa9ec78e256df60d0f703908fc12e.jpg'});
            }

6.OC调用js

// 将分享结果返回给js
    NSString *jsStr = [NSString stringWithFormat:@"shareResult('%@','%@','%@')",title,content,url];
    [self.webView evaluateJavaScript:jsStr completionHandler:^(id _Nullable result, NSError * _Nullable error) {
        NSLog(@"%@----%@",result, error);
    }];

注意方法调用，传递参数根据在js中的参数格式。

以上交互操作，还是鉴于WKWebview操作的基础上，使用MessageHandler来实现。