async void OnContactSelected(object sender, Xamarin.Forms.SelectedItemChangedEventArgs e)
{
// We need to check if SelectedItem is null because further below
// we de-select the selected item. This will raise another ItemSelected
// event, so this method will be called straight away. If we don't
// check for null here, we'll get a NullReferenceException.
if (contacts.SelectedItem == null)
return;
var selectedContact = e.SelectedItem as FormsContact;
// We de-select the selected item, so when we come back to the Contacts
// page we can tap it again and navigate to ContactDetail.
contacts.SelectedItem = null;
var page = new ContactDetailPage(selectedContact);
page.ContactUpdated += (source, contact) =>
{
// When the target page raises ContactUpdated event, we get
// notified and update properties of the selected contact.
// Here we are dealing with a small class with only a few
// properties. If working with a larger class, you may want
// to look at AutoMapper, which is a convention-based mapping
// tool.
selectedContact.Id = contact.Id;
selectedContact.FirstName = contact.FirstName;
selectedContact.LastName = contact.LastName;
selectedContact.Phone = contact.Phone;
selectedContact.Email = contact.Email;
selectedContact.IsBlocked = contact.IsBlocked;
};
await Navigation.PushAsync(page);
}
async void OnAddContact(object sender, System.EventArgs e)
{
var page = new ContactDetailPage(new FormsContact());
// We can subscribe to the ContactAdded event using a lambda expression.
// If you're not familiar with this syntax, watch my C# Advanced course.
page.ContactAdded += (source, contact) =>
{
// ContactAdded event is raised when the user taps the Done button.
// Here, we get notified and add this contact to our
// ObservableCollection.
_contacts.Add(contact);
};
await Navigation.PushAsync(page);
}