Mg Dana Mg Dana - 5 months ago 34
Swift Question

I want to return Boolean after firebase code is executed

I'm retrieving data from Firebase Google. I'm checking the data i received is expire or not.

func checkBought(movieName : String) -> Bool{

var yesOrNo = false

boughtRef.observeEventType(.Value, withBlock: { (snap) in

if snap.value![movieName]! != nil {
if self.timestamp > snap.value![movieName]! as! Double {
//expire
print("expire")
yesOrNo = false
} else {
//not expire
print("not expire")
yesOrNo = true
}
} else {
//not bought yet
print("No movie")
yesOrNo = false

}
})

return yesOrNo
}


Now, the return statement is returning before the firebase code is executed and change the value of yesOrNo.

Answer

The classic:

You cannot return anything from a method which contains an asynchronous task

You need a completion block, simply

func checkBought(movieName : String, completion:(Bool) -> Void) {

    boughtRef.observeEventType(.Value, withBlock: { (snap) in

    if snap.value![movieName]! != nil {
      if self.timestamp > snap.value![movieName]! as! Double {
        //expire
        print("expire")
        completion(false)
      } else {
        //not expire
        print("not expire")
        completion(true)
      }
    } else {
      //not bought yet
      print("No movie")
      completion(false)

    }
  })
}

Or easier

func checkBought(movieName : String, completion:(Bool) -> Void) {
  boughtRef.observeEventType(.Value, withBlock: { (snap) in
    if let movieStamp = snap.value![movieName] as? Double where self.timestamp <= movieStamp {
      //not expire
      print("not expire")
      completion(true)
    } else {
      // expire or not bought yet
      print("expire or no movie")
      completion(false)
    }
  })
}

And call it with

checkBought("Foo") { flag in
   print(flag)
}