WKWebView之oc调用js以及WKUserScript JS注入

oc调用js就特别简单了，只需WKWebView调用

• (void)evaluateJavaScript:completionHandler:方法即可。

/* @abstract Evaluates the given JavaScript string.
 @param javaScriptString The JavaScript string to evaluate.
 @param completionHandler A block to invoke when script evaluation completes or fails.
 @discussion The completionHandler is passed the result of the script evaluation or an error.
*/
- (void)evaluateJavaScript:(NSString *)javaScriptString completionHandler:(void (^ _Nullable)(_Nullable id, NSError * _Nullable error))completionHandler;

WKUserScript JS注入

在WebKit框架中，我们还可以预先添加JS方法，供其他人员调用。WKUserScript就是帮助我们完成JS注入的类，它能帮助我们在页面填充前或js填充完成后调用。核心方法。

/*! @abstract Returns an initialized user script that can be added to a @link WKUserContentController @/link.
 @param source The script source.
 @param injectionTime When the script should be injected.
 @param forMainFrameOnly Whether the script should be injected into all frames or just the main frame.
 */
- (instancetype)initWithSource:(NSString *)source injectionTime:(WKUserScriptInjectionTime)injectionTime forMainFrameOnly:(BOOL)forMainFrameOnly;

#pragma mark - get方法
- (WKWebView *)webView {
    if (_webView == nil) {
        // js配置
        WKUserContentController *userContentController = [[WKUserContentController alloc] init];
        [userContentController addScriptMessageHandler:self name:@"jsCallOC"];
        // js注入，注入一个alert方法，页面加载完毕弹出一个对话框。
        NSString *javaScriptSource = @"alert(\"WKUserScript注入js\");";
        WKUserScript *userScript = [[WKUserScript alloc] initWithSource:javaScriptSource injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];// forMainFrameOnly:NO(全局窗口)，yes（只限主窗口）
        [userContentController addUserScript:userScript];

        // WKWebView的配置
        WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
        configuration.userContentController = userContentController;

        // 显示WKWebView
        _webView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:configuration];
        [self.view addSubview:_webView];
    }
    return _webView;
}

同时实现代理WKUIDelegate的方法：

#pragma mark alert弹出框
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler {
    NSLog(@"%s",__FUNCTION__);
    // 确定按钮
    UIAlertAction *alertAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        completionHandler();
    }];
    // alert弹出框
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:message message:nil preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:alertAction];
    [self presentViewController:alertController animated:YES completion:nil];
}