title: How to create unique image ID each time upload is pressed using Flutter/Firebase?
body: <p>I'm trying to make an image upload button and link it to Firebase such that each time the button is pressed, the image is sent to Firebase Storage. Here are the relevant snippets of my code:</p>
  
  <pre><code>  // Files, and references
    File _imageFile;
    StorageReference _reference =
        FirebaseStorage.instance.ref().child('myimage.jpg');
  
    Future uploadImage() async {
      // upload the image to firebase storage
      StorageUploadTask uploadTask = _reference.putFile(_imageFile);
      StorageTaskSnapshot taskSnapshot = await uploadTask.onComplete;
  
      // update the uploaded state to true after uploading the image to firebase
      setState(() {
        _uploaded = true;
      });
    }
    // if no image file exists, then a blank container shows - else, it will upload 
    //the image upon press
    _imageFile == null
                  ? Container()
                  : RaisedButton(
                      color: Colors.orange[800],
                      child: Text("Upload to Firebase Storage"),
                      onPressed: () {uploadImage();}),
  </code></pre>
  
  <p>However, each time I press this button, the image overwrites the pre-existing image with the same name, and I was wondering if there's a way to make it so that each time I press the button, the name of the image changes, and as a result the original image isn't overridden. I'd greatly appreciate any help I could get as I'm very new to Flutter and Firebase.</p>
  
  <p>Thank you!</p>