AlertDialog：创建一个警告对话框。

  _AlertDialog() async {
    var alertRel = await showDialog(
        context: context,
        builder: (context) {
          return AlertDialog(
            title: Text("提示!"),
            content: Text("确定要删除吗"),
            actions: <Widget>[
              FlatButton(
                child: Text("取消"),
                onPressed: () {
                  Navigator.pop(context, 'Cancle');
                },
              ),
              FlatButton(
                child: Text("确定"),
                onPressed: () {
                  Navigator.pop(context, 'Ok');
                },
              )
            ],
          );
        }
    );
  }

SimpleDialog：创建一个简单的对话框。

_SimpleDialog() async {
    var simpleRel = await showDialog(
        context: context,
        builder: (BuildContext context) {
          return SimpleDialog(
            title: Text("select 单选按钮框"),
            children: <Widget>[
              SimpleDialogOption(
                child: Text("Option A"),
                onPressed: () {
                  Navigator.pop(context, 'Option A');
                },
              ),
              Divider(),
              SimpleDialogOption(
                child: Text("Option B"),
                onPressed: () {
                  Navigator.pop(context, 'Option B');
                },
              ),
              Divider(),
              SimpleDialogOption(
                child: Text("Option C"),
                onPressed: () {
                  Navigator.pop(context, 'Option C');
                },
              )
            ],
          );
        }
    );
  }

showModalBottomSheet：创建一个底部页面。

  _showModalBottomSheet() async {
    var actionSheet = await showModalBottomSheet(
        context: context,
        builder: (builder) {
          return Container(
            height: 200,
            child: Column(
              children: <Widget>[
                ListTile(
                  title: Text("分享 A"),
                  onTap: () {
                    Navigator.pop(context, 'A');
                  },
                ),
                ListTile(
                  title: Text("分享 B"),
                  onTap: () {
                    Navigator.pop(context, 'B');
                  },
                ),
                ListTile(
                  title: Text("分享 C"),
                  onTap: () {
                    Navigator.pop(context, 'C');
                  },
                )
              ],
            ),
          );
        }
    );
  }

showToast：调用将显示消息的平台的 showToast

pub地址：https://pub.dev/packages/fluttertoast

  _showToast() {
    Fluttertoast.showToast(
        msg: "This is Short Toast",
        toastLength: Toast.LENGTH_SHORT,
        timeInSecForIosWeb: 1);
  }