I'm newbie in MVVM . I have two xaml pages. the second one cannot be accessed ( Locked ) unless the button from the first page (Introduction page) has been clicked. How can I do that?

The lock page has this code.

```
<Frame Grid.Row="0" Grid.Column="1" BackgroundColor="LightGray" IsVisible="{Binding LockPage}">
                <Frame.GestureRecognizers>
                    <TapGestureRecognizer Tapped="Tap_Lock" />
                </Frame.GestureRecognizers>
                <Label Text="Locked"/>
            </Frame>

```

The Introduction page has this code.

```
<StackLayout>
        <Label Text="This is only a simple Introduction Text."/>
        <Label Text=""/>
        <Button Text="Lets Go!!" Command="{Binding UnlockPageCommand}" Clicked="Tap_Next"/>
</StackLayout>

```

This is the the class LockModule.cs

```
 public class LockModule : INotifyPropertyChanged
{

    public LockModule()
    {
        UnlockPageCommand = new Command(UnlockPage);
    }

    bool lockPage = true;
    public event PropertyChangedEventHandler PropertyChanged;

    void OnPropertyChanged(string lockpage)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(lockpage));
    }

    public bool LockPage
    {
        get { return lockPage; }
        set
        {
                lockPage = value;

            OnPropertyChanged(nameof(LockPage));
        }
    }

    public Command UnlockPageCommand { get; }

    void UnlockPage()
    {
        if (lockPage == true)
        {
            lockPage = false;
        }
        else
        {
            lockPage = true;
        }
        OnPropertyChanged(nameof(LockPage));
    }
}

```

and it's not working......
['https://Stackoverflow.com/questions/51989213', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/10161534/']
There are two files needed to be modified about port 8081:

1.react-native/local-cli/server/server.js - default

2.react-native/React/React.xcodeproj/project.pbxproj - replace all the 8081 ports with your desired ports in above two files

Your port will be changed.
You need to overwrite the `RCT_METRO_PORT` macro variable to ensure your app points to the correct port when running via xcode or `react-native run-ios`. This can be done by opening the Pods project within your workspace, navigating to Build Settings and adding a Preprocessor Macro. For example `RCT_METRO_PORT=7777`, if the port you are using is `7777`.

[![enter image description here](https://i.stack.imgur.com/aYw06.png)](https://i.stack.imgur.com/aYw06.png)