Xamarin Forms-另一个页面中的访问变量

Question

I have a function in my MainPage.xaml.cs, and when it is called I would like to change the text on a label in another page called Dashboard.xaml.cs

How do I change variables and call functions between files in Xamarin Forms?

Answer 1

Pages are just classes, and you can communicate between them like any class: using public methods, public properties, public events, etc

However, using Form's built in MessagingCenter might be the best method:

// send a message TO an instance of MyPage
MessagingCenter.Send<MyPage, string> (this, "MessageName", some_string_arg);

// in MyPage, listen for the Message
MessagingCenter.Subscribe<MyPage> (this, "MessageName", (sender, args) => {
    // args will contain the value passed in Send
});

Answer 2

Provided that you have a reference to the instance of the Page, you can invoke methods or set properties on that instance.

In 2.3.6, you'll even be able to set a x:FieldModifier and modify the field values directly.

But don't do any of that. Use a Mvvm pattern, Bind your Pages, and let the ViewModels communicate between each other. And your Pages will be modified accordingly.

Answer 3

Every view in Xamarin is a class, you can instantiate a variable of the type View, where View is the page you want to access. For example:

I have a view called Works. To access (public) functions and variables contained within the view, I write code like this:

Works MyTestVariable;
var SomeResult = MyTestVariable.FunctionInWorksClass(aParameter);

The function contained in the Works view is executed and the value is returned to the var in the calling view.