Technique to insert new row in UITableView - objective-c

Question

Currently i'm trying to create a nested list view in iOS, this table would be similar to a p-list, which mean every time users tap on plus sign at the beginning of each cell, new rows would appear below it.
At the moment, I think the solution would be: when click on the button, update the datasource of the table, then insert new rows below the clicked index (this is where I got stuck!).
The original data source is an array of string: {"a", "b", "c", "d"}
The data that is added after each record is: {"sub-1", "sub-2", "sub-3"}
I'm writing this demo in C#, but I'm able to understand swift and obj-c so feel free to post any language that you like!
My code currently include 3 main classes: CustomtableSource.cs CustomTableViewCell.cs and ExpandableListViewController.cs
CustomTableSource.cs:
class CustomTableSource : UITableViewSource
{
private List<Book> _books;
string CellIdentifier = "TableCell";
public CustomTableSource(List<Book> books)
{
_books = books;
}
public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath)
{
var customCell = tableView.DequeueReusableCell(CellIdentifier) as CustomTableViewCell;
Book book = _books[indexPath.Row];
UIImage img = UIImage.FromFile("Images/closed.png");
if (customCell == null)
{
customCell = new CustomTableViewCell(CellIdentifier);
customCell.UpdateCell(book.BookTitle, img);
}
return customCell;
}
public override nint RowsInSection(UITableView tableview, nint rowInSection)
{
return _books.Count;
}
public override nint NumberOfSections(UITableView tableView)
{
return 1;
}
}
CustomTableViewCell.cs
public class CustomTableViewCell : UITableViewCell
{
private UIButton _button;// = UIButton.FromType(UIButtonType.Custom);
private UILabel _title;
public CustomTableViewCell(string cellId) : base (UITableViewCellStyle.Default, cellId)
{
SelectionStyle = UITableViewCellSelectionStyle.Gray;
ContentView.BackgroundColor = UIColor.Clear;
_button = UIButton.FromType(UIButtonType.Custom);
/* _button.TouchUpInside += (sender, args) =>
{
_button.SetImage(UIImage.FromFile("Images/open.png"), UIControlState.Normal);
};*/
_title = new UILabel();
_title.BackgroundColor = UIColor.Clear;
ContentView.AddSubviews(new UIView[] {_button, _title});
}
public void UpdateCell(string title, UIImage image)
{
_button.SetImage(image, UIControlState.Normal);
_title.Text = title;
}
public override void LayoutSubviews()
{
base.LayoutSubviews();
_button.Frame = new CGRect(12, 22, 10, 10);
_title.Frame = new CGRect(30, 5, ContentView.Bounds.Width, ContentView.Bounds.Height);
}
}
ExpandableListViewController.cs:
public class ExpandableListViewController : UIViewController
{
private UITableView _tableView;
private UIButton _rowButton;
public ExpandableListViewController() : base("ExpandableListViewController", null)
{
}
public override void ViewDidLoad()
{
base.ViewDidLoad();
var width = View.Bounds.Width;
var height = View.Bounds.Height;
_tableView = new UITableView(new CGRect(0, 0, width, height));
//_rowButton = CustomTableViewCell._button;
_tableView.AutoresizingMask = UIViewAutoresizing.All;
List<Book> books = new List<Book>();
books.Add(new Book() { BookTitle = "C programming", Level = 0 });
books.Add(new Book() { BookTitle = "Beginner", Level = 1 });
books.Add(new Book() { BookTitle = "Moderate", Level = 1 });
books.Add(new Book() { BookTitle = "Advanced", Level = 1 });
books.Add(new Book() { BookTitle = "Java programming", Level = 2 });
books.Add(new Book() { BookTitle = "Basic", Level = 1 });
books.Add(new Book() { BookTitle = "Java Swing", Level = 1 });
books.Add(new Book() { BookTitle = "Pascal programming", Level = 0 });
//books.Add(new Book() { BookTitle = "CoBol programming", Level = 0 });
CustomTableSource tableSource = new CustomTableSource(books);
_tableView.Source = tableSource;
Add(_tableView);
/*_rowButton.TouchUpInside += (sender, args) =>
{
_rowButton.SetImage(UIImage.FromFile("Images/open.png"), UIControlState.Normal);
_tableView.BeginUpdates();
books.Add(new Book() { BookTitle = "CoBol programming", Level = 0 });
_tableView.ReloadData();
_tableView.EndUpdates();
};*/
}
}
A screenshot of what I have done:

Answer 1

Add these code to CustomTableSource.cs to raise an event when user select a row.
public event EventHandler<int> OnRowItemSelected;
public override void RowSelected(UITableView tableView, Foundation.NSIndexPath indexPath)
{
if (OnRowItemSelected != null)
{
OnRowItemSelected(tableView, indexPath.Row);
}
tableView.DeselectRow(indexPath, true);
}
From ExpandableListViewController.cs, subscribe row selected event, add new book when it's raised and reload table then
tableSource. OnRowItemSelected += (s, e) => {
//Insert new sub item list
books.Insert(e, new Book { /*init*/ } );
//reload table
_tableView.ReloadData();
};