需求：

调起网页，监听返回的点击事件，返回上一层

Snip20170612_5.png

1. 写个类，并需要导入#import <JavaScriptCore/JavaScriptCore.h>，所需代码不上100行

- (void)viewDidLoad{
    [super viewDidLoad];
    UIWebView *web =[[UIWebView alloc]initWithFrame:CGRectMake(0,-0, LYScreen_Width, LYScreen_Height-64)];
    web.delegate = self;
    [self.view addSubview:web];
    NSURLRequest *httpRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:LYlytUrl]];
    [web loadRequest:httpRequest];

}
- (void)webViewDidFinishLoad:(UIWebView *)webView{
    
    JSContext *jsContext = [webView valueForKeyPath:@"documentView.webView.mainFrame.javaScriptContext"];
       LYWeakSelf;
        /// 关联打印异常
        jsContext.exceptionHandler = ^(JSContext *context, JSValue *exceptionValue) {
            context.exception = exceptionValue;
        };
        jsContext[@"closeTopicView"] = ^{           dispatch_async(dispatch_get_main_queue(), ^{
            [weakSelf.navigationController popViewControllerAnimated:YES];
            });
        };
}

2.在其需要处导入上面写的类名，然后进行初始化，push过去即可。