问快速显示的firebase photoUrl不能用图像选择器替换图像

EN

func displayProfilePic(user: FIRUser?){

let photoURL = user?.photoURL
struct last {
  static var photoURL: NSURL? = nil
}
last.photoURL = photoURL;  // to prevent earlier image overwrites later one.
if let photoURL = photoURL {
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), {
    let data = NSData.init(contentsOfURL: photoURL)
    if let data = data {
      let image = UIImage.init(data: data)
      dispatch_async(dispatch_get_main_queue(), {
        if (photoURL == last.photoURL) {
          self.profilePic.image = image
        }
      })
    }
  })
} else {
  profilePic.image = UIImage.init(named: "DefaultPic")
}

func openGallary(){

if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.SavedPhotosAlbum){
  print("Pick Photo")

  self.imagePicker.delegate = self
  self.imagePicker.sourceType = UIImagePickerControllerSourceType.PhotoLibrary
  self.imagePicker.allowsEditing = true
  self.presentViewController(self.imagePicker, animated: true, completion: nil)
}
}

func openCamera(){
if(UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera)){
  self.imagePicker.sourceType = UIImagePickerControllerSourceType.Camera
  self.imagePicker.allowsEditing = true
  self.presentViewController(self.imagePicker, animated: true, completion: nil)

}else{
  print("you got no camara")
}
}

func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
self.dismissViewControllerAnimated(true, completion: { () -> Void in

})
profilePic.image = image
}