使用WKWebView进行JavaScript方法调用：

**步骤1.**导入webkit类

目标C：#import <WebKit/WebKit.h>
Swift：import WebKit

**第二步.**创建WKWebView示例（可惜只能通过脚本完成）

Obj-C @property (strong, nonatomic) WKWebView *wkWebView;
Swift var wkWebView: WKWebView? = WKWebView()

**步骤3.**然后在viewDidLoad中

目标C：

WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
    
    NSString *scriptSourceCode = @"your javascript code here";
    WKUserScript *script = [[WKUserScript alloc] initWithSource:source injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES];

    WKUserContentController *controller = [[WKUserContentController alloc] init];
    [controller addUserScript:script];

    configuration.userContentController = controller;
    
    _wkWebView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:configuration];
    
    [self.view addSubview:_wkWebView];

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雨燕：

let configuration = WKWebViewConfiguration()
    let controller = WKUserContentController()
    
    let scriptSourceCode = "your javascript code here"
    let script = WKUserScript(source: scriptSourceCode, injectionTime: WKUserScriptInjectionTime.AtDocumentStart, forMainFrameOnly: true)
    controller.addUserScript(script)

    configuration.userContentController = controller
    
    self.wkWebView = WKWebView(frame: self.view.frame, configuration: configuration)
    
    self.view.addSubview(self.wkWebView!)

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步骤4在wkWebView中加载HTML字符串（或loadRequest）：

目标C：

[_wkWebView loadHTMLString:_desiredHTML baseURL:[[NSBundle mainBundle] bundleURL]];

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雨燕：

self.wkWebView?.loadHTMLString(_desiredHTML, baseURL: NSBundle.mainBundle().bundleURL)

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第五步.调用WKWebView中包含的JavaScript中的方法

目标C：

NSString *callMethod = [NSString stringWithFormat:@"existingMethodWithParam(%@)", stringParam];

    [_wkWebView evaluateJavaScript:callMethod
             completionHandler:^(id obj, NSError *error) {
                 
                 if (error)
                 {
                     NSLog(@"ERROR evaluating JavaScript - %@", error);
                 }
                 else 
                 {
                     NSLog(@"Returned value - %@", obj); //if the javascript method has a return type
                 }
             }];

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雨燕：

let callMethod = "existingMethodWithParam()"
self.wkWebView?.evaluateJavaScript(callMethod) { obj, error in
    print(obj)
    print(error)
}

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