[英]Set the Size of a UICollectionViewCell based on the screen width and the number of columns Xamarin.iOS
我正在使用Xamarin.iOS
構建應用程序。 應用程序的第一個屏幕我使用了UICollectionView
來顯示多個類別。 我希望類別顯示在兩列中,但這里有一個問題。 我在storyBoard.In
上手動設置了單元格的大小。在像iPhone 3.5
英寸這樣的小屏幕上,只出現一列,同時在iPhone 6
或6Plus
等大屏幕中出現兩列,但列之間有很多空格。
表View有一個我們可以在TableViewSource
, GetRowHeight
覆蓋的方法。 有沒有辦法根據屏幕寬度和列數設置collectionViewCell
的大小。
這是我在My App中實現CollectionView的方式:
SectionViewSource.cs
public class SectionViewSource: UICollectionViewSource
{
public List<SectionCategory> rows { get; set; }
public ViewController owner { get; set;}
public SectionViewSource (List<SectionCategory> _rows, ViewController _owner)
{
rows = _rows;
owner = _owner;
}
public override nint NumberOfSections (UICollectionView collectionView)
{
return 1;
}
public override nint GetItemsCount (UICollectionView collectionView, nint section)
{
return rows.Count;
}
public override bool ShouldHighlightItem (UICollectionView collectionView, NSIndexPath indexPath)
{
return true;
}
public override void ItemHighlighted (UICollectionView collectionView, NSIndexPath indexPath)
{
var cell = (SectionViewCell)collectionView.CellForItem (indexPath);
cell.mainLabel.Alpha = 0.5f;
}
public override bool CanPerformAction (UICollectionView collectionView, Selector action, NSIndexPath indexPath, NSObject sender)
{
return true;
}
public override void PerformAction (UICollectionView collectionView, Selector action, NSIndexPath indexPath, NSObject sender)
{
System.Diagnostics.Debug.WriteLine ("code to perform action");
}
public override void ItemUnhighlighted (UICollectionView collectionView, NSIndexPath indexPath)
{
var cell = (SectionViewCell)collectionView.CellForItem (indexPath);
cell.mainLabel.Alpha = 1.0f;
}
public override UICollectionViewCell GetCell (UICollectionView collectionView, NSIndexPath indexPath)
{
var cell = (SectionViewCell)collectionView.DequeueReusableCell (SectionViewCell.CellID, indexPath);
cell.UpdateCell (rows [indexPath.Row].sectionName,rows [indexPath.Row].sectionUrlImage);
return cell;
}
}
SectionViewCell.cs
public class SectionViewCell: UICollectionViewCell
{
public UILabel mainLabel;
public UIImageView _imageView;
public static NSString CellID = new NSString("customCollectionCell");
[Export ("initWithFrame:")]
public SectionViewCell (CGRect frame) : base(frame)
{
BackgroundView = new UIView { BackgroundColor = UIColor.Orange };
ContentView.BackgroundColor = UIColor.LightGray;
_imageView = new UIImageView ();
mainLabel = new UILabel ();
mainLabel.TextColor = UIColor.White;
ContentView.AddSubviews (new UIView[] { _imageView, mainLabel });
}
public void UpdateCell (string text, string url) {
mainLabel.Text = text;
mainLabel.LineBreakMode = UILineBreakMode.TailTruncation;
mainLabel.Lines = 2;
mainLabel.Font = UIFont.FromName("Optima-Bold", 18f);
ImageService.LoadUrl(url).Into(_imageView);
_imageView.Frame = new CGRect (0, 0, ContentView.Bounds.Width, ContentView.Bounds.Height);
mainLabel.Frame = new CGRect (10, 10, ContentView.Bounds.Width-20, 40);
}
}
ViewController.cs
sectionGrid.RegisterClassForCell(typeof(SectionViewCell), SectionViewCell.CellID);
sectionGrid.Source = new SectionViewSource (sectionCategories,this);
嘗試設置CollectionViewLayout,如下所示:
// Flow Layout
var flowLayout = new UICollectionViewFlowLayout (){
ItemSize = new CGSize ((float)UIScreen.MainScreen.Bounds.Size.Width/2.0f, (float)UIScreen.MainScreen.Bounds.Size.Width/2.0f),
HeaderReferenceSize = new CGSize (100, 100),
SectionInset = new UIEdgeInsets (0,0,0,0),
ScrollDirection = UICollectionViewScrollDirection.Vertical,
MinimumInteritemSpacing = 0, // minimum spacing between cells
MinimumLineSpacing = 0 // minimum spacing between rows if ScrollDirection is Vertical or between columns if Horizontal
};
simpleCollectionViewController = new UICollectionViewController (flowLayout);
創造這樣的東西:
更新
你可以試試這個:
var flowLayout = new UICollectionViewFlowLayout (){
ItemSize = new CGSize ((float)UIScreen.MainScreen.Bounds.Size.Width/2.0f, (float)UIScreen.MainScreen.Bounds.Size.Width/2.0f),
HeaderReferenceSize = new CGSize (100, 100),
SectionInset = new UIEdgeInsets (0,0,0,0),
ScrollDirection = UICollectionViewScrollDirection.Vertical,
MinimumInteritemSpacing = 0, // minimum spacing between cells
MinimumLineSpacing = 0 // minimum spacing between rows if ScrollDirection is Vertical or between columns if Horizontal
};
sectionGrid.PerformBatchUpdates (() => {
sectionGrid.CollectionViewLayout.InvalidateLayout ();
sectionGrid.SetCollectionViewLayout (flowLayout, false);
});
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