Get value from JS Promise / async function from inside JSContext

Question

I am running the SDK for JavaScript from JSContext, however I cannot get the values ​​from any asynchronous SDK function. I can get the JavaScript promise from JSContext, but I can’t figure out how to solve it. I tried many ways to get value from a promise, but each of them failed.

If I try something like the following, I get [object Promise]back:

return self.jsContext.evaluateScript("new Promise(resolve => { setTimeout(300, () => resolve([1, 2, 3])) })")!

If I connect thendirectly to JS, I get [object Promise]more:

return self.jsContext.evaluateScript("new Promise(resolve => { setTimeout(300, () => resolve([1, 2, 3])) }).then(val => val.json())")

If I try to call a method from Swift, I still get [object Promise]:

let jsPromise = self.jsContext.evaluateScript("new Promise(resolve => { setTimeout(300, () => resolve([1, 2, 3])) })")
let promiseResult = jsPromise?.invokeMethod("then", withArguments: ["val => { return val.json() }"])
return promiseResult!

JS Promise, Swift then, , ( , ):

self.jsContext.evaluateScript("let tempVar = 'Nothing has happened yet!'")
let jsPromise = self.jsContext.evaluateScript("new Promise(resolve => { setTimeout(300, () => resolve([1, 2, 3])) })")
let promiseResult = jsPromise?.invokeMethod("then", withArguments: ["val => { tempVar = val }"])
let tempVar = self.jsContext.evaluateScript("tempVar")
return tempVar!

await Promise , JSContext, IU EXC_BAD_INSTRUCTION:

let jsPromise = self.jsContext.evaluateScript("let someVar = await new Promise(resolve => { setTimeout(300, () => resolve([1, 2, 3])) })")
return self.jsContext.evaluateScript("someVar")!

, , - , Swift.

Answer 1

, Promise JSContext. , setTimout, setInterval .., JSContext.

Swift Javascript, JSContext. , , JSContext.

var logValue = "" {
    didSet {
        print(logValue)
    }
}
//block we can pass to JSContext as JS function
let showLogScript: @convention(block) (String) -> Void = { value in
    logValue = value
}
let jsContext = JSContext()

//set exceptionHandler block
jsContext?.exceptionHandler = {
    (ctx: JSContext!, value: JSValue!) in
    print(value)
}
//make showLog function available to JSContext
jsContext?.setObject(unsafeBitCast(showLogScript, to: AnyObject.self), forKeyedSubscript: "showLog" as (NSCopying & NSObjectProtocol))

jsContext!.evaluateScript("showLog('this is my first name')") //this works
jsContext!.evaluateScript("showLog(setTimeout.name)") //it has issue