CODEWITHSUNDEEP
iosobjective-cjavascriptcore
oskob
oskob

Reputation: 1376

JavasScriptCore asynchronous callback

I'm trying to figure out a way to execute some Javascript and return the result through a completion block, but for some reason, the callback never fires.

+ (void)doSomethingWithCompletionHandler:(void (^)(NSError* error, NSString *result))completionHandler;
{
    JSContext __block *context;
    context = [[MyJSContext alloc] initWithVirtualMachine:[[JSVirtualMachine alloc] init]];
    context[@"done"] = (id) ^(NSString *result)
    {
        context = nil;
        completionHandler(nil, result);
    };

    // this works
    // [context evaluateScript:@"(function(){ done('immediate'); })()"];

    // this does not
    [context evaluateScript:@"(function(){ setTimeout(function(){ done('delayed'); }, 1000); })()"];

}

As soon as I try to making it async, simulated here by using a timeout, the block in context[@"done"] is never called.

I've extended JSContext to make sure it is not deallocated when it goes out of scope (hence the __black hack).

Am I approaching this the wrong way?

Upvotes: 0

Views: 761

Answers (2)

John
John

Reputation: 26

I guess the problem is there is no setTimeout function in JavaScriptCore. You can write it yourself or to look for some existed libraries for that like (self promotion!) https://github.com/artemyarulin/JSCoreBom

P.S. It is really good idea to have at least setTimeout, because many-many-many libraries are using that

P.P.S Use JSContext setExceptionHandler in order to catch errors like that

Upvotes: 1

oskob
oskob

Reputation: 1376

It seems that functions like setTimeout and setInterval is not available in JavaScriptCore, and since the sandboxed nature of it, I assume that I won't be needing any async functions either, so lets just return and be done with it ;)

Upvotes: 0

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