'AnyObject'无法转换为'String'

Question

I've got this error when i try to query the parse database. I'm using this code found into the parse documentation and modified a bit. I need to take all records saved into 'elencoBirre' table, my 'test' variable is of type 'AnyObject' and i'm not able to "convert" this to a simple String, i don't get how to do. I've tried to force 'as NSString/String' but when i launch the app it stuck.

var appoggio2 = [String]()  

func loadDataCarrello(){

    self.appoggio2.removeAll()
    var findTimelineData:PFQuery = PFQuery (className: "Carrello")
    findTimelineData.whereKeyExists("elencoBirre")
    findTimelineData.findObjectsInBackgroundWithBlock{
        (objects:[AnyObject]!, error:NSError!)->Void in
        if error == nil{
            for object in objects{
                let test:PFObject = object as PFObject

                //Here is the error 'AnyObject' is not convertible to 'String'
                self.appoggio2.append(test.objectForKey("elencoBirre"))
            }                
        }
        println(self.appoggio2)
    }        
}

Answer 1

The objectForKey method does not guarantee results of a specific type. To cast it and append when the cast is successful, use the following:

if let elencoBirre = test.objectForKey("elencoBirre") as? String {
  self.appoggio2.append(elencoBirre)
}

You have stated that you actually expect this object to be an array. Try this instead:

if let elencoBirre = test.objectForKey("elencoBirre") as? [String] {
  for str in elencoBirre {
    self.appoggio2.append(str)
  }
}