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Detailed explanation of sample code using JavaScriptCore to realize OC and JS interaction

黄舟Original: 2017-03-28 14:09:291038browse

JavaScriptCore is an important part of webkit, mainly parsing JS and provide an execution environment. The following article mainly introduces you to the relevant information about using JavaScriptCore to realize the interaction between OC and JS. The introduction in the article is very detailed. Friends who need it can refer to it. Let’s take a look.

JavascriptCore

JavascriptCore is an important part of webkit. It mainly parses JS and provides an execution environment. After iOS7, Apple launched it on the iPhone platform, which is a great development. It facilitates our operation of js.

First create a webView and read the local html file

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

In the demo, we have to implement 4 situations

JS calls OC
JS calls OC and passes parameters
OC calls JS
OC calls JS and passes parameters

The code in the html file is as follows

<html>
<head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 <script type="text/javascript">
 function showAlert(){
  alert(&#39;OC call JS with no argument&#39;);
 }
 function showAlertWithString(string){
  alert(string);
 }
 function callOCWithArgument() {
  jsCallOCWithArgument(&#39;参数1 &#39;,&#39;参数2 &#39;,&#39;参数3&#39;);
 }
 </script>
</head>
<body>
 </br>
 </br>
 </br>
 </br>
 <form>
  <button type=&#39;button&#39; onclick=&#39;callOC()&#39;>jsCallOC</button>
  <button type=&#39;button&#39; onclick=&#39;callOCWithArgument()&#39;>jsCallOCWithArgument</button>
 </form>
</body>
</html>

JS calls OC

In webView's proxy method webViewDidFinishLoad

-(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];
  });
 }; 
}

We define a block and save it to the context. In fact, it is converted into a function named callOC in JS. Then we execute this function directly, and what is called is the content in our block.

The passed parameters can be accepted through the [JSContext currentArguments] array, which is the JSValue object.

##OC calls JS

to initialize two Buttons, and implement the following method

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

 [_context evaluatescript:@"showAlertWithString(&#39;OC call JS with arguments&#39;)"];
// [_context[@"showAlertWithString"] callWithArguments:@[@"OC call JS with arguments"]];
}

in the click event

Implement OC calling JS

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