CODEWITHSUNDEEP
data-bindingxamarinxamarin.iosmvvmcrossuinavigationitem
TheDeveloper
TheDeveloper

Reputation: 1217

Xamarin iOS: MvvMCross Binding back button of navigationItem

I want to bind the back button of the navigation item and whenever user clicks the back button I want to execute some code binded to it in view model.

My current code:

View:

var bSet = this.CreateBindingSet<xView, xViewModel>();
            bSet.Bind(NavigationItem.LeftBarButtonItem).To(vm => vm.CheckIfLoading);
            //bSet.Bind(NavigationItem.BackBarButtonItem).To(vm => vm.CheckIfLoading);

ViewModel:

private ICommand checkIfLoading;
public xViewModel()
            : base() 
        {
            this.messenger = mvxMessenger;
            checkIfLoading = new MvxCommand(DoRefresh);
        }
public  ICommand CheckIfLoading { get { return checkIfLoading; } }
private async void DoRefresh()
{
  await Task.Delay(5000);
}

When ever I hit the back button, I want it to hit DoRefresh(), but its not. Can anyone point out the error or help me resolve it ?

Upvotes: 1

Views: 893

Answers (1)

Mark Verkiel
Mark Verkiel

Reputation: 1239

You can use the following code to bind Clicked to your ICommand:

this.AddBindings(new Dictionary<object, string>()
{
    { NavigationItem.LeftBarButtonItem, "Clicked CheckIfLoading" }
});

Side note

The following line might not work if Clicked isn't the default binding: bSet.Bind(NavigationItem.LeftBarButtonItem).To(vm => vm.CheckIfLoading);

Other ways to bind to a specific property can be achieved by using the .For(labda) method as following:

bSet.Bind(NavigationItem.LeftBarButtonItem).For(lb => lb.Clicked).To(vm => vm.CheckIfLoading);

But in this case that won't work since lb.Clicked expects a left hand sided action ( += or -= )

For more information about binding take a look at https://github.com/MvvmCross/MvvmCross/wiki/databinding

Upvotes: 3

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