UICollectionView with section layout issue in Xamarin Native - ios

Question

I have UIcollectionView with 8 sections. Each section has a dedicated array as the data source. I want to add an item to each section on a button press. UICollectionView scroll direction set to Horizontal because I want the sections to be vertical direction.
Everything working fine in Xcode project(Xib and Objective-C) as this screenshot(Red colored items are the items added on button press).
When I do the same implementation in Xamarin ios, the layout become a mess after press the button as bellow.
My code as bellow
public partial class GridViewController : UIViewController
{
CVSource source;
int MAX_NUMBER_OF_ROWS = 4;
public GridViewController(IntPtr handle) : base(handle)
{
}
public override void ViewDidLoad()
{
base.ViewDidLoad();
// Perform any additional setup after loading the view, typically from a nib.
//this.collectionView.SetNeedsDisplay();
this.collectionView.RegisterClassForCell(typeof(ItemCell), ItemCell.CellId);
source = new CVSource();
this.collectionView.DataSource = source;
}
partial void AddButtonPressed(UIButton sender)
{
Console.WriteLine("Add button pressed");
MAX_NUMBER_OF_ROWS = MAX_NUMBER_OF_ROWS + 1;
source.AddItem();
collectionView.Layer.RemoveAllAnimations();
collectionView.ReloadData();
ViewDidLayoutSubviews();
}
public override void ViewDidLayoutSubviews()
{
base.ViewDidLayoutSubviews();
collectionView.Frame = new CoreGraphics.CGRect(collectionView.Frame.Location.X, collectionView.Frame.Location.Y, collectionView.Frame.Size.Width, MAX_NUMBER_OF_ROWS * 40);
btnAdd.Frame = new CoreGraphics.CGRect(btnAdd.Frame.Location.X, collectionView.Frame.Location.Y + collectionView.Frame.Size.Height + 10, btnAdd.Frame.Size.Width, btnAdd.Frame.Size.Height);
}
public override void DidReceiveMemoryWarning()
{
base.DidReceiveMemoryWarning();
// Release any cached data, images, etc that aren't in use.
}
DataSource class
class CVSource : UICollectionViewSource
{
List<string> arr1 = new List<string> { "40", "30"};
List<string> arr2 = new List<string> { "25", "22" };
List<string> arr3 = new List<string> { "35", "67" };
List<string> arr4 = new List<string> { "26", "12" };
List<string> arr5 = new List<string> { "27", "21", };
List<string> arr6 = new List<string> { "12", "45" };
List<string> arr7 = new List<string> { "34", "67" };
List<string> arr8 = new List<string> { "21", "44", };
public override nint NumberOfSections(UICollectionView collectionView)
{
return 8;
}
public override nint GetItemsCount(UICollectionView collectionView, nint section)
{
if ((int)section == 0)
return arr1.Count;
else if ((int)section == 1)
return arr2.Count;
else if ((int)section == 2)
return arr3.Count;
else if ((int)section == 3)
return arr4.Count;
else if ((int)section == 4)
return arr5.Count;
else if ((int)section == 5)
return arr6.Count;
else if ((int)section == 6)
return arr7.Count;
else if ((int)section == 7)
return arr8.Count;
return 0;
}
public override UICollectionViewCell GetCell(UICollectionView collectionView, Foundation.NSIndexPath indexPath)
{
var itemCell = (ItemCell)collectionView.DequeueReusableCell(ItemCell.CellId, indexPath);
if (indexPath.Section == 0)
{
itemCell.SetText(arr1[indexPath.Row]);
}
else if (indexPath.Section == 1)
{
itemCell.SetText(arr2[indexPath.Row]);
}
else if (indexPath.Section == 2)
{
itemCell.SetText(arr3[indexPath.Row]);
}
else if (indexPath.Section == 3)
{
itemCell.SetText(arr4[indexPath.Row]);
}
else if (indexPath.Section == 4)
{
itemCell.SetText(arr5[indexPath.Row]);
}
else if (indexPath.Section == 5)
{
itemCell.SetText(arr6[indexPath.Row]);
}
else if (indexPath.Section == 6)
{
itemCell.SetText(arr7[indexPath.Row]);
}
else if (indexPath.Section == 7)
itemCell.SetText(arr8[(indexPath.Row)]);
return itemCell;
}
public override void ItemSelected(UICollectionView collectionView, NSIndexPath indexPath)
{
Console.WriteLine("Row selected "+ indexPath.Row);
}
public void AddItem()
{
arr1.Add("0");
arr2.Add("0");
arr3.Add("0");
arr4.Add("0");
arr5.Add("0");
arr6.Add("0");
arr7.Add("0");
arr8.Add("0");
}
}
ItemCell class
public partial class ItemCell : UICollectionViewCell
{
public static readonly NSString CellId = new NSString("ItemCell");
public static UITextField txtFld;
[Export("initWithFrame:")]
public ItemCell(CGRect frame) : base(frame)
{
BackgroundView = new UIView { BackgroundColor = UIColor.Orange };
SelectedBackgroundView = new UIView { BackgroundColor = UIColor.Green };
ContentView.Layer.BorderColor = UIColor.LightGray.CGColor;
ContentView.Layer.BorderWidth = 2.0f;
ContentView.BackgroundColor = UIColor.White;
ContentView.Transform = CGAffineTransform.MakeScale(0.8f, 0.8f);
txtFld = new UITextField() { Frame = new CGRect(5.0, 5.0, 60.0, 30.0), KeyboardType = UIKeyboardType.DecimalPad };
}
}
Im not a Xamarin developer, appreciate any comments/suggestions from Xamarin experts

Answer 1

Maybe you miss UICollectionViewLayout to set for collectionView , you can set the GridLayout for collectionView to have a try .
this.collectionView.SetCollectionViewLayout(new GridLayout(), true); //add CollectionViewLayout
this.collectionView.RegisterClassForCell(typeof(ItemCell), ItemCell.CellId);
GridLayout inherits from UICollectionViewFlowLayout in Xamrarin iOS :
public class GridLayout : UICollectionViewFlowLayout
{
public GridLayout ()
{
}
public override bool ShouldInvalidateLayoutForBoundsChange (CGRect newBounds)
{
return true;
}
public override UICollectionViewLayoutAttributes LayoutAttributesForItem (NSIndexPath path)
{
return base.LayoutAttributesForItem (path);
}
public override UICollectionViewLayoutAttributes[] LayoutAttributesForElementsInRect (CGRect rect)
{
return base.LayoutAttributesForElementsInRect (rect);
}
}
The effect :
Affter tried the shared code , the effect as follow :
The different with your codes only here :
public ViewController (IntPtr handle) : base (handle)
{
collectionView = new UICollectionView(new CGRect(0, 0, UIScreen.MainScreen.Bounds.Size.Width, 300), new GridLayout());
collectionView.RegisterClassForCell(typeof(ItemCell), ItemCell.CellId);
//collectionView.SetCollectionViewLayout(new GridLayout(), true);
collectionView.BackgroundColor = UIColor.Blue;
source = new CVSource();
collectionView.DataSource = source;
View.AddSubview(collectionView);
button = new UIButton(new CGRect(150, 400, 100, 50));
button.SetTitle("Hello", UIControlState.Normal);
button.BackgroundColor = UIColor.Red;
View.AddSubview(button);
button.TouchUpInside += Button_TouchUpInside;
}
Note : I use code to create Interface , and set GridLayout for CollectionView .Here is the sample link .