iOS中使用JavaScriptCore实现OC与JS双向交互

 NSURL* htmlURL = [[NSBundle mainBundle] URLForResource: @"demo" withExtension: @"html"];
[_webView loadRequest: [NSURLRequest requestWithURL: htmlURL]];

<html>
<head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 <script type="text/javascript">
 function showAlert(){
  alert('OC call JS with no argument');
 }
 function showAlertWithString(string){
  alert(string);
 }
 function callOCWithArgument() {
  jsCallOCWithArgument('参数1 ','参数2 ','参数3');
 }
 </script>
</head>
<body>
 </br>
 </br>
 </br>
 </br>
 <form>
  <button type='button' onclick='callOC()'>jsCallOC</button>
  <button type='button' onclick='callOCWithArgument()'>jsCallOCWithArgument</button>
 </form>
</body>
</html>

-(void)webViewDidFinishLoad:(UIWebView *)webView
{

 _context = [webView valueForKeyPath:@"documentView.webView.mainFrame.javaScriptContext"];
 __weak typeof(self) weakSelf = self;
 _context.exceptionHandler = ^(JSContext *context, JSValue *exception) {
  weakSelf.context.exception = exception;
 };

 //js调用OC
 _context[@"callOC"] = ^() {
  NSArray *args = [JSContext currentArguments];
  for (JSValue *jsVal in args) {
   NSLog(@"%@", jsVal.toString);
  }
  dispatch_async(dispatch_get_main_queue(), ^{
   UIAlertController *alertView = [UIAlertController alertControllerWithTitle:@"arguments" message:@"JS Call OC With No Argument" preferredStyle:UIAlertControllerStyleAlert];
   UIAlertAction * action = [UIAlertAction actionWithTitle:@"Done" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

   }];
   [alertView addAction:action];
   [weakSelf presentViewController:alertView animated:YES completion:nil];
  });
 };

 _context[@"jsCallOCWithArgument"] = ^() {
  NSArray *args = [JSContext currentArguments];
  NSMutableString * stirng = [NSMutableString string];
  for (JSValue * value in args) {
   [stirng appendString:value.toString];
  }
  dispatch_async(dispatch_get_main_queue(), ^{
   UIAlertController *alertView = [UIAlertController alertControllerWithTitle:@"arguments" message:stirng preferredStyle:UIAlertControllerStyleAlert];
   UIAlertAction * action = [UIAlertAction actionWithTitle:@"Done" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
   }];
   [alertView addAction:action];
   [weakSelf presentViewController:alertView animated:YES completion:nil];
  });
 }; 
}

- (IBAction)callJS:(id)sender {
 [_context evaluateScript:@"showAlert()"];
}
- (IBAction)callJSWithArguments:(id)sender {

 [_context evaluateScript:@"showAlertWithString('OC call JS with arguments')"];
// [_context[@"showAlertWithString"] callWithArguments:@[@"OC call JS with arguments"]];
}