ShowDialogを別のファイルから呼び出したい。

Question

前提・実現したいこと

ShowDialogを別のファイルから呼び出したい。

発生している問題・エラーメッセージ

════════ Exception caught by rendering library ═════════════════════════════════
RenderBox was not laid out: RenderPhysicalShape#81ed4 relayoutBoundary=up2
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1940 pos 12: 'hasSize'

The relevant error-causing widget was
AlertDialog
lib/conponets_widgets/show_alert_dialog.dart:35

show_alert_page.dart

class SignInPage extends StatelessWidget {
  SignInPage({@required this.auth});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Time Tricker.'),
      ),
      body: Container(
        alignment: Alignment.center,
        padding: const EdgeInsets.symmetric(horizontal: 22.0, vertical: 40.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'SigIn Page',
              style: TextStyle(
                fontSize: 22.0,
                fontWeight: FontWeight.bold,
              ),
            ),
            SizedBox(
              height: 32.0,
            ),
            SocialSignInButton(
                color: Colors.white,
                imagePath: 'images/simple-logo.png',
                text: Text(
                  'Show Alert.',
                  style: DefaultButtonStyle(),
                ),
                onPressed: () async{
                  ***こちらは上記のエラーが発生する。***
                  showAlertDialog(context,
                      title: 'test alert',
                      content: 'sample text.',
                      defaultActionText: 'Ok',
                      cancelActionText: 'cancel');
                }),
            SizedBox(
              height: 12.0,
            ),
            SocialSignInButton(
                color: Colors.indigo,
                imagePath: 'images/sample2-logo.png',
                text: Text(
                  'Show Alert2.',
                  style: DefaultButtonStyle().copyWith(color: Colors.white),
                ),
                onPressed: () {
                  ***こちらは正常に呼び出せる。***
                  showDialog(
                    context: context,
                    builder: (context) => AlertDialog(
                      title: Text('Hello'),
                      content: Text('Smaple text'),
                      actions: <Widget>[
                        TextButton(
                          onPressed: () => Navigator.of(context).pop(false),
                          child: Text('cancel'),
                        ),
                        TextButton(
                          onPressed: () => Navigator.of(context).pop(true),
                          child: Text('ok'),
                        ),
                      ],
                    ),
                  );
                }),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

TextStyle DefaultButtonStyle() {
  return TextStyle(
      fontSize: 18.0, fontWeight: FontWeight.w300, color: Colors.black87);
}

###show_alert_dialog.dart

Future<bool> showAlertDialog(
  BuildContext context, {
  @required String title,
  @required String content,
  String cancelActionText,
  @required String defaultActionText,
}) {
  if (!Platform.isIOS) {
    return showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text(title),
        content: Text(content),
        actions: <Widget>[
          if (cancelActionText != null) ...{
            TextButton(
              onPressed: () => Navigator.of(context).pop(false),
              child: Text(cancelActionText),
            ),
          },
          TextButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: Text(defaultActionText),
          ),
        ],
      ),
    );
  }
  return showCupertinoDialog(
    context: context,
    builder: (context) => AlertDialog(
      title: Text(title),
      content: Text(content),
      actions: <Widget>[
        CupertinoDialogAction(
          onPressed: () => Navigator.of(context).pop(true),
          child: Text(defaultActionText),
        ),
      ],
    ),
  );
}

iOS,Androidどちらもエラーが発生します。

###試したこと
show_alert_dialog.dart内を変更

showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text(title),
        ***Containerでラップして高さと幅を持たせる***
        content: Container(width: 300, height: 400, child: Text(content)),
        actions: <Widget>[
          if (cancelActionText != null) ...{
            TextButton(
              onPressed: () => Navigator.of(context).pop(false),
              child: Text(cancelActionText),
            ),
          },
          TextButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: Text(defaultActionText),
          ),
        ],
      ),
    );

Answer 1

Iosで呼び出す際はAlertDialogではなく、CupertinoAlertDialogを使う。

showCupertinoDialog(
    context: context,
    ***ここを変更***
    builder: (context) => CupertinoAlertDialog(
      title: Text(title),
      content:　child: Text(content),
      actions: <Widget>[
        CupertinoDialogAction(
          onPressed: () => Navigator.of(context).pop(true),
          child: Text(defaultActionText),
        ),
      ],
    ),
  );