上篇文章讲过，oc和js交互，oc调用js关键的方法是
- (nullable NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script;
这篇文章讲的是js如何调用oc，js调用oc的关键方法是
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType

一、写一个简单的html网页，3个p标签。

372E5D6D-6840-4D6F-928E-49F6583927C2.png

js代码

image.png

二、实现UIWebViewDelegate的代理方法。
request.URL.scheme 协议。
request.URL.absoluteString 绝对路径。
//每当webView即将发送一个请求之前，都会调用这个方法

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{
NSLog(@"scheme = %@",request.URL.scheme);
NSLog(@"absoluteString = %@",request.URL.absoluteString);
NSArray *array = [request.URL.absoluteString componentsSeparatedByString:@"?"];
NSLog(@"array = %@",array);
//判断连接是否存在
if ([request.URL.scheme isEqualToString:@"clickp"]) {
    //说明没有参数
    if (array.count==1) {

        SEL sel = NSSelectorFromString(request.URL.scheme);
        [self performSelector:sel withObject:nil withObject:nil];

    }else if(array.count == 2){//说明有1个参数

        SEL sel = NSSelectorFromString([NSString stringWithFormat:@"%@:",request.URL.scheme]);
        [self performSelector:sel withObject:[array lastObject] withObject:nil];

    }else if (array.count == 3){//说明有2个参数

        SEL sel = NSSelectorFromString([NSString stringWithFormat:@"%@:message:",request.URL.scheme]);
        [self performSelector:sel withObject:array[1] withObject:[array lastObject]];

    }

}

三、点击p标签，执行UIWebViewDelegate的代理方法，调用oc代码

//点击第一个p标签
- (void)clickp{
self.showTop.text = @"点击了第一个p标签";
}

//点击第二个p标签
- (void)clickp:(NSString *)message{
NSString *new = [message stringByRemovingPercentEncoding];
self.showCenter.text = new;
}

//点击第三个p标签

- (void)clickp:(NSString *)firstMessage message:(NSString *)lastMessage{
NSString *firstParam = [firstMessage stringByRemovingPercentEncoding];
NSString *lastParam = [lastMessage stringByRemovingPercentEncoding];
self.showBottom.text = [NSString stringWithFormat:@"%@ %@",firstParam,lastParam];
}

实例图片:

jscalloc.gif