JSContext *context=[_webView valueForKeyPath:@"documentView.webView.mainFrame.javaScriptContext"];
NSString*funtionString=[NSString stringWithFormat:@"javascript:showExpressNumber(‘%@‘)",qrString];
[context evaluateScript:funtionString];//通过oc方法调用js的
原文:http://www.cnblogs.com/xiwanxiang190351/p/7112231.html