Xamarin表单，我的视图模型中的命令如何到达/连接现有按钮？

Question

This is my viewmodel where I have the command, that changes the value of an int. I want to bind this command to a Button.

public SharedViewModel()
{
    ClickCommand = new Command (() => CurrentValue = CurrentValue + 1);
}

public ICommand ClickCommand 
{
    get { return clickCommand; }
    set
    {
        clickCommand = value;
        OnPropertyChanged("ClickCommand");
    }
}

And this is my ContentPage where I have a button named click1 :

public MenuPage ()
{
    var ourSharedView = new SharedViewModel ();
    ourSharedView.ClickCommand; //and this is the command, I have no idea how I should connect this with my existing button below though. This 
}

void click1 (object s, EventArgs a)
{
  // how can I connect this clickbutton to my command? 
}

Answer 1

From the code behind, you can do this

myButton.Command = ourSharedView.ClickCommand;

you should remove the Button's Click handler - you do not need it if you are using a Command

Answer 2

First of all creating a View Model from the View(Page) is not a good idea. Page should be created after VM is exist and use it's data.

I recomend you to read the Data binding basics , MVVM binding .

As for your question assume you have View Model with ICommand property, set binding of the button command in page to it:

public class CustomPage : ContentPage
{
    private Button btn {get;set;}

    public CustomPage()
    {
        if(btn == null)
            btn = createButtonFunction();
        btn.SetBinding<ViewModelClassName>(Button.CommandProperty, vm => vm.CommandFromViewModel)
        //btn.SetBinding(Button.CommandProperty, "CommandFromViewModel")//other way to set binding
    }

}

Commented line does same work as privious, use one of them.

PS Forget to mention that to work propertly BindingContext property of page has to be set to the View Model of this page.