iOS与JS的相互调用除了URL拦截（iOS与JS(一)：使用URL拦截的方式进行JS与OC互相调用）外，还可以使用WKWebView的中的MessageHandler来实现。
MessageHandler是什么呢？以代码来说明，比较好理解。
在OC中初始化WKWebView是，添加如下代码:
[self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Location"];
那么在JS中就可以使用：
window.webkit.messageHandlers.Location.postMessage(null);
JS中的Location就对应OC中的name，postMessage后的参数就是JS传给OC的参数，类型可以是 NSNumber, NSString, NSDate, NSArray, NSDictionary, and NSNull。
JS回调OC时，就回调WKScriptMessageHandler的- (void)userContentController:([WKUserContentController](apple-reference-documentation://hcracoR5p2) *)userContentController didReceiveScriptMessage:([WKScriptMessage](apple-reference-documentation://hcD3KQdcJY) *)message;方法，这边的message是WKScriptMessage， message.name就是“Location”，message.body就是postMessage后的参数。
下面看完整的🌰：
html的代码
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf8">
<script language="javascript">
var ctuapp_share_img="www.baidu.com";
function locationClick() {
window.webkit.messageHandlers.Location.postMessage(null);
}
function shake() {
window.webkit.messageHandlers.Shake.postMessage(null);
}
function payClick(){
window.webkit.messageHandlers.Pay.postMessage({order_no:'201511120981234',channel:'wx',amount:1,subject:'粉色外套'});
}
function setLocation(location) {
alert(location)
document.getElementById("returnValue").value = location;
}
function payResult(str) {
alert(str);
document.getElementById("returnValue").value = str;
}
</script>
</head>
<body>
<h1>这是按钮调用</h1>
<input type="button" value="获取定位" onclick="locationClick()" /><br><br>
<input type="button" value="震动一下" onclick="shake()" /><br><br>
<input type="button" value="支付" onclick="payClick()" /><br><br>
<h1>这是文件上传</h1>
<input type="file" /><br><br>
<h1>这是回调结果展示区</h1>
<textarea id ="returnValue" type="value" rows="5" cols="50"></textarea>
</body>
</html>
初始化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];
}
添加 MessageHandler
为了防止循环引用，结束时释放。
- (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
[self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Location"];
[self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Shake"];
[self.webView.configuration.userContentController addScriptMessageHandler:self name:@"Pay"];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Location"];
[self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Shake"];
[self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Pay"];
}
实现WKUIDelegate和WKScriptMessageHandler协议方法
#pragma mark - WKUIDelegate
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler
{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"提醒" message:message preferredStyle:UIAlertControllerStyleAlert];
[alert addAction:[UIAlertAction actionWithTitle:@"知道了" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
completionHandler();
}]];
[self presentViewController:alert animated:YES completion:nil];
}
#pragma mark - WKScriptMessageHandler
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message
{
// message.body -- Allowed types are NSNumber, NSString, NSDate, NSArray,NSDictionary, and NSNull.
NSLog(@"body:%@",message.body);
if ([message.name isEqualToString:@"Location"]) {
[self getLocation];
} else if ([message.name isEqualToString:@"Shake"]) {
[self shakeAction];
} else if ([message.name isEqualToString:@"Pay"]) {
[self payWithParams:message.body];
}
}
效果：
Swift的和OC类型，代码我也一起写了
代码： 90-iOSJS 中的 OCJSMessageHandler 和 SwiftJSMessageHandler
