利用JavaScriptCore实现简单的功能（阶乘）

 #import "RootViewController.h"
 #import <JavaScriptCore/JavaScriptCore.h>

 @interface RootViewController ()
 @end

 @implementation RootViewController

 - (void)viewDidLoad {
     [super viewDidLoad];

     JSContext *context = [[JSContext alloc] init];
     context[@"factorial"] = ^(int x){
         int factorial = ;
         for (; x > ; x--) {
             factorial *= x;
         }
         return factorial;
     };
     [context evaluateScript:@"var fiveFactorial = factorial(5);"];
     JSValue *fiveFactorial = context[@"fiveFactorial"];
     NSLog(@"5! = %@",fiveFactorial);

 }

 @end