Flutter- call function after function - flutter

Question

I want to call function2 after function1 finished.
To do that I did like that.
this is function 1.
Future _uploadImages() async {
setState(() {isUploading = true;});
images.forEach((image) async {
await image.requestThumbnail(300, 300).then((_) async {
final int date = DateTime.now().millisecondsSinceEpoch;
final String storageId = '$date$uid';
final StorageReference ref =
FirebaseStorage.instance.ref().child('images').child(storageId);
final file = image.thumbData.buffer.asUint8List();
StorageUploadTask uploadTask = ref.putData(file);
Uri downloadUrl = (await uploadTask.future).downloadUrl;
final String url = downloadUrl.toString();
imageUrls.add(url);
});
});
}
this is function 2
Future _writeImageInfo() async {
await _uploadImages().then((_) async {
await Firestore.instance.collection('post').document(uid).setData({
'imageUrls': imageUrls,
}).then((_) {
Navigator.of(context).pop();
});
}
But console says function2's imageUrls called when list length = 0 because it's called before function 1 finished.
I don't know why that function not called after function 1.
How can I make this right?

Answer 1

This happens because of your images.forEach. The .forEach doesn't work with async callback. Therefore it doesn't wait the end of each the foreach to continue the function.
In general, don't use .forEach in dart anyway. Dart did a great job on the for keyword directly.
So ultimately, you should do the following:
for (final image in images) {
...
}