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Which Item is user focused in listview xamarin forms

I am a student learning xamarin forms, I am trying to create a basic chat app in this I want to know how to get position of current item in listview that's user watching. When a new message received i want to know if user is at bottom or not if at bottom focus the new and if not at the bottom then just add not by adding focus to it.

you get the selected item from the Xamarin.Forms.ListView.SelectedItem property of your ListView.
If your ListView.ItemSource is of a type that allows using IndexOf you can now do something like
int position = (yourlistview.ItemSource as ObservableCollection<your type>).IndexOf(yourlistview.SelectedItem)
Update:
ok I think i understood what you want.
In most cases more than one item is currently shown when using a listview. So their exists not a single index
but i think you just want to know if the last item of the list is visible/the user has scrolled to the end?
If so ListView has an ItemAppearing event. I use it for example to load more data from an websource if the user scrolled through the first 100 items.
You could do something like this
listview.ItemAppearing += listviewItemAppearing;
listview.ItemDisappearing += listviewItemDisappearing;
bool m_scrolledToEnd;
private void listviewItemDisappearing(object sender, ItemVisibilityEventArgs e)
{
if(e.Item == yourlastiem)
m_scrolledToEnd = false;
}
private void listviewItemAppearing(object sender, ItemVisibilityEventArgs e)
{
if(e.Item == yourlastiem)
m_scrolledToEnd = true;
}
if you realy need to know if a specific index is shown you could create a List<int> m_idxlist;
and in the appearing event add the index of the item to the list
and in the disappearing event remove the index of the item from the list.
Then you will have a list where all indexes of the items currently shown are stored.

From the Documentation
ListView supports selection of one item at a time. Selection is on by
default. When a user taps an item, two events are fired: ItemTapped
and ItemSelected. Note that tapping the same item twice will not fire
multiple ItemSelected events, but will fire multiple ItemTapped
events. Also note that ItemSelected will be called if an item is
deselected.
To detect selecting an item, you can add a method, onSelection:
void OnSelection (object sender, SelectedItemChangedEventArgs e)
{
if (e.SelectedItem == null) {
return; //ItemSelected is called on deselection, which results in SelectedItem being set to null
}
DisplayAlert ("Item Selected", e.SelectedItem.ToString (), "Ok");
//((ListView)sender).SelectedItem = null; //uncomment line if you want to disable the visual selection state.
}
To disable selection just set the selectedItem to null:
SelectionDemoList.ItemSelected += (sender, e) => {
((ListView)sender).SelectedItem = null;
};

How access to selected items of a ListView from another class? in WPF C#

I have two views of WPF (Vista1.xaml and Vista2.xaml), and they are part of a MainWindow.xaml.
In the Vista1.xaml i have a listview, where the user selects some items by clicking and the Vista2.xaml has a button.
I want that when the user clicks on the button of Vista2.xaml, get the items that the user previously selected in the listview of Vista1.xaml.
I have class in the Vista1.xaml.cs ListViewItem_PreviewMouseLeftButtonDown method that captures the user selects the item in the listview.
the code is as follows
private void ListViewItem_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var item = sender as ListViewItem;
if (item != null && item.IsSelected)
{
...
}
}
I appreciate your help

Add a public property to you MainPage that contains the data you want to pass between Vista1 and Vista2. Then, in your event handler of Vista1, set the property and on the button click of Vista2 read the property.

Deselect combobox item

I have a databound combobox:
using(DataContext db = new DataContext())
{
var ds = db.Managers.Select(q=> new { q.ManagerName, q.ManagerID});
cmbbx_Managers.BindingContext = new BindingContext();
cmbbx_Managers.DataSource = ds;
cmbbx_Managers.DisplayMember = "ManagerName";
cmbbx_Managers.ValueMember = "ManagerID";
}
When the form loads neither item is selected, but when the user chooses an item it cannot be deselected. I tried to add cmbbx_Managers.items.Insert(0, "none"), but it does not solve the problem, because it is impossible to add a new item to the databound combobox.
How do I allow a user to deselect a combobox item?

To add an item to your databound ComboBox, you need to add your item to your list which is being bound to your ComboBox.
var managers = managerRepository.GetAll();
managers.Insert(0, new Manager() { ManagerID = 0, ManagerName = "(None)");
managersComboBox.DisplayMember = "ManagerName";
managersComboBox.ValueMember = "ManagerID";
managersComboBox.DataSource = managers;
So, to deselect, you now simply need to set the ComboBox.SelectedIndex = 0, or else, use the BindingSource.CurrencyManager.
Also, one needs to set the DataSource property in last line per this precision brought to us by #RamonAroujo from his comment. I updated my answer accordingly.

The way you "deselect" an item in a drop-down ComboBox is by selecting a different item.
There is no "deselect" option for a ComboBox—something always has to be selected. If you want to simulate the behavior where nothing is selected, you'll need to add a <none> item (or equivalent) to the ComboBox. The user can then select this option when they want to "deselect".
It is poor design that, by default, a ComboBox appears without any item selected, since the user can never recreate that state. You should never allow this to happen. In the control's (or parent form's) initializer, always set the ComboBox to a default value.
If you really need a widget that allows clearing the current selection, then you should use a ListView or ListBox control instead.

To deselect an item suppose the user presses the Esc key, you could subscribe to the comboxBox KeyDown event and set selected index to none.
private void cmbbx_Managers_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Escape && !this.cmbbx_Managers.DroppedDown)
{
this.cmbbx_Managers.SelectedIndex = -1;
}
}

How to react to deselected Item in FileOpenPickerUI?

I have a problem with my FileOpenPicker-app. If I select an item in my GridView, the item will be added to the FileOpenPickerUI, it works fine. But if I deselect an Item in the FileOpenPickerUI, it won´t deselect in my GridView.
So I added the Event:
_fileOpenPickerUI.FileRemoved += FilePickerUI_FileRemoved;
This is the method:
private async void FilePickerUI_FileRemoved(FileOpenPickerUI sender, FileRemovedEventArgs args)
{
//DO SOMETHIG
}
This is the documentation:
http://msdn.microsoft.com/de-de/library/windows/apps/windows.storage.pickers.provider.fileopenpickerui.fileremoved
How can I react to the deselected item? How can I deselect it in my GridView?

There is no two way binding between the FileOpenPickerUI item selection/deselection and GridView item selection/deselection. If you can access the GridView's selected item within the FilePickerUI_FileRemovedhandler, you can explicitly set the SelectedIndexproperty to -1.

List view Highlight selected

Quite a simple question but I think its going to prove much harder than it sounds
I'd like to keep the selection of a listview item there when the focus leaves the list view, at the moment I've set the hideselection property to false and that's fine.. it does cause a VERY light gray selection to stay after the list view loses focus, so my question is, how can I properly show that that item is still selected so that the user will recognize that, something like changing the rows text colour or background colour? or just keeping it highlighted as when first selected the whole row turns blue?
I've had a look through intelisense and can't seem to find anything for a row or item or selected item's individual colour property?
It must exist though because selected items have their own background colour, where would I be able to change that?
Oh and the list view does need to stay in details view, which means I can't use the only method that I've been able to find whilst googling
thanks

Here's a solution for a ListView that does not allow multiple selections and
does not have images (e.g. checkboxes).
Set event handlers for the ListView (in this example it's named listView1):
DrawItem
Leave (invoked when the ListView's focus is lost)
Declare a global int variable (i.e. a member of the Form that contains the ListView,
in this example it's named gListView1LostFocusItem) and assign it the value -1
int gListView1LostFocusItem = -1;
Implement the event handlers as follows:
private void listView1_Leave(object sender, EventArgs e)
{
// Set the global int variable (gListView1LostFocusItem) to
// the index of the selected item that just lost focus
gListView1LostFocusItem = listView1.FocusedItem.Index;
}
private void listView1_DrawItem(object sender, DrawListViewItemEventArgs e)
{
// If this item is the selected item
if (e.Item.Selected)
{
// If the selected item just lost the focus
if (gListView1LostFocusItem == e.Item.Index)
{
// Set the colors to whatever you want (I would suggest
// something less intense than the colors used for the
// selected item when it has focus)
e.Item.ForeColor = Color.Black;
e.Item.BackColor = Color.LightBlue;
// Indicate that this action does not need to be performed
// again (until the next time the selected item loses focus)
gListView1LostFocusItem = -1;
}
else if (listView1.Focused) // If the selected item has focus
{
// Set the colors to the normal colors for a selected item
e.Item.ForeColor = SystemColors.HighlightText;
e.Item.BackColor = SystemColors.Highlight;
}
}
else
{
// Set the normal colors for items that are not selected
e.Item.ForeColor = listView1.ForeColor;
e.Item.BackColor = listView1.BackColor;
}
e.DrawBackground();
e.DrawText();
}
Note: This solution can result in some flicker. A fix for this involves subclassing the ListView control so you
can change the protected property DoubleBuffered to true.
public class ListViewEx : ListView
{
public ListViewEx() : base()
{
this.DoubleBuffered = true;
}
}
I created a class library of the above class so that I could add it to the toolbox.

A possible solution might be this answer to an another question:
How to change listview selected row backcolor even when focus on another control?