Ios UICollectionView装饰视图

是否有人为iOS 6 UICollectionView实现了装饰视图？这是不可能的

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查找有关在web上实现装饰视图的任何教程。基本上，在我的应用程序中，我有多个部分，我只想在每个部分后面显示一个装饰视图。这应该是简单的实现，但我没有运气。这让我快发疯了。。。谢谢。

我通过自定义布局获得了以下内容：

创建UICollectionReusableView的子类，例如向其添加UIImageView：

@implementation AULYFloorPlanDecorationViewCell

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        UIImage *backgroundImage = [UIImage imageNamed:@"Layout.png"];
        UIImageView *imageView = [[UIImageView alloc] initWithFrame:frame];
        imageView.image = backgroundImage;
        [self addSubview:imageView];
    }
    return self;
}

@end

然后在viewDidLoad中的控制器中，用以下代码注册此子类（用自定义布局替换代码）

然后在自定义布局中实现以下方法（或类似方法）：

-（UICollectionViewLayoutAttributes*）layoutAttributesForDecorationViewOfKind:（NSString*）decorationViewKind atIndexPath:（NSIndexPath*）indexPath
{
UICollectionViewLayoutAttributes*layoutAttributes=[UICollectionViewLayoutAttributes layoutAttributes layoutAttributes ForDecorrationViewOfKind:decorationViewKind withIndexPath:indexPath]；
layoutAttributes.frame=CGRectMake（0.0,0.0，self.collectionViewContentSize.width，self.collectionViewContentSize.height）；
layouttributes.zIndex=-1；
返回布局属性；
}
-（NSArray*）布局属性ForElementsInRect:（CGRect）rect
{
NSMutableArray*allAttributes=[[NSMutableArray alloc]initWithCapacity:4]；
[allAttributes addObject:[self-layoutAttributesForDecorationViewOfKind:@“FloorPlan”atIndexPath:[NSIndexPath indexPathForItem:0第0节]]；
对于（NSInteger i=0；i<[self.collectionView numberofitemsin部分：0]；i++）
{
NSIndexPath*indexPath=[NSIndexPath indexPathForItem:i第1节：0]；
UICollectionViewLayoutAttributes*layoutAttributes=[self-layoutAttributesForItemAtIndexPath:indexPath]；
[allAttributes addObject:layoutAttributes]；
}
返回所有属性；
}

似乎没有相关文档，但以下文档让我走上了正确的道路：

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更新：可能最好将UICollectionReusableView子类化为装饰视图，而不是UICollectionViewCell

public class DecorationView : UICollectionReusableView
{
    private static NSString classId = new NSString ("DecorationView");
    public static NSString ClassId { get { return classId; } }

    UIImageView blueMarble;

    [Export("initWithFrame:")]
    public DecorationView (RectangleF frame) : base(frame)
    {
        blueMarble = new UIImageView (UIImage.FromBundle ("bluemarble.png"));

        AddSubview (blueMarble);    
    }
}


public class SimpleCollectionViewController : UICollectionViewController
{
    public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();
        //Register the cell class (code for AnimalCell snipped)
        CollectionView.RegisterClassForCell (typeof(AnimalCell), AnimalCell.ClassId);
        //Register the supplementary view class (code for SideSupplement snipped)
        CollectionView.RegisterClassForSupplementaryView (typeof(SideSupplement), UICollectionElementKindSection.Header, SideSupplement.ClassId);

        //Register the decoration view
        CollectionView.CollectionViewLayout.RegisterClassForDecorationView (typeof(DecorationView), DecorationView.ClassId);
    }

 //...snip...
}

public class LineLayout : UICollectionViewFlowLayout
{
    public override UICollectionViewLayoutAttributes[] LayoutAttributesForElementsInRect (RectangleF rect)
    {
        var array = base.LayoutAttributesForElementsInRect (rect);
        /* 
        ...snip content relating to cell layout...
        */
        //Add decoration view
        var attributesWithDecoration = new List<UICollectionViewLayoutAttributes> (array.Length + 1);
        attributesWithDecoration.AddRange (array);
        var decorationIndexPath = NSIndexPath.FromIndex (0);
        var decorationAttributes = LayoutAttributesForDecorationView (DecorationView.ClassId, decorationIndexPath);
        attributesWithDecoration.Add (decorationAttributes);

        var extended = attributesWithDecoration.ToArray<UICollectionViewLayoutAttributes> ();

        return extended;
    }

    public override UICollectionViewLayoutAttributes LayoutAttributesForDecorationView (NSString kind, NSIndexPath indexPath)
    {
        var layoutAttributes = UICollectionViewLayoutAttributes.CreateForDecorationView (kind, indexPath);
        layoutAttributes.Frame = new RectangleF (0, 0, CollectionView.ContentSize.Width, CollectionView.ContentSize.Height);
        layoutAttributes.ZIndex = -1;
        return layoutAttributes;
    }
//...snip...
}

公共类装饰视图：UICollectionReusableView { 私有静态NSString classId=新NSString（“装饰视图”）； 公共静态NSString ClassId{get{return ClassId；}} UIImageView蓝色大理石； [导出（“initWithFrame:”）] 公共装饰视图（矩形框架）：基础（框架） { Blue大理石=新的UIImageView（UIImage.FromBundle（“blueMarble.png”）； 添加子视图（蓝色大理石）； } } 公共类SimpleCollectionViewController:UICollectionViewController { 公共覆盖无效ViewDidLoad（） { base.ViewDidLoad（）； //注册单元类（AnimalCell snipped的代码） CollectionView.RegisterClassForCell（typeof（AnimalCell），AnimalCell.ClassId）； //注册补充视图类（侧边补充剪下的代码） CollectionView.RegisterClassForSupplementaryView（typeof（SideReplacement），UICollectionElementKindSection.Header，SideReplacement.ClassId）； //注册装饰视图 CollectionView.CollectionViewLayout.RegisterClassForDecorationView（typeof（DecorationView），DecorationView.ClassId）； } //…剪断。。。 } 公共类LineLayout:UICollectionViewFlowLayout { 公共覆盖UICollectionViewLayoutAttributes[]LayoutAttributesForElementsInRect（RectangleF rect） { var数组=base.layouttributesforementsinrect（rect）； /* …剪切与单元格布局相关的内容。。。 */ //添加装饰视图 var attributesWithDecoration=新列表（array.Length+1）； attributesWithDecoration.AddRange（数组）； var decorationIndexPath=nsindepath.FromIndex（0）； var decorationAttributes=layouttributesfordecorationview（DecorationView.ClassId，decorationIndexPath）； 添加（装饰属性）； var extended=attributesWithDecoration.ToArray（）； 回报延长； } 公共重写UICollectionViewLayoutAttributes LayoutAttributesForDecorationView（NSString类，NSIndexPath indexPath） { var layoutAttributes=UICollectionViewLayoutAttributes.CreateForDecorationView（种类，indexPath）； LayoutAttribute.Frame=新矩形F（0，0，CollectionView.ContentSize.Width，CollectionView.ContentSize.Height）； layouttributes.ZIndex=-1； 返回布局属性； } //…剪断。。。 } 最终结果类似于：

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这是Swift中的集合视图布局装饰视图教程（这是Swift 3，Xcode 8 seed 6）

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装饰视图不是UICollectionView功能；它们本质上属于UICollectionViewLayout。没有UICollectionView方法（或委托或数据源方法）提到装饰视图。UICollectionView对它们一无所知；它只是做它被告知的事情

要提供任何装饰视图，需要UICollectionViewLayout子类；这个子类可以自由定义自己的属性和委托协议方法，这些方法可以自定义装饰视图的配置方式，但这完全取决于您

为了说明这一点，我将为UICollectionViewFlowLayout创建子类，以便在集合视图的内容矩形顶部添加一个标题标签。这可能是对装饰视图的愚蠢使用，但它完美地说明了基本原则。为了简单起见，我将从硬编码开始，让客户机无法自定义此视图的任何方面

在布局子类中实现装饰视图有四个步骤：

class MyTitleView : UICollectionReusableView {
    weak var lab : UILabel!
    override init(frame: CGRect) {
        super.init(frame:frame)
        let lab = UILabel(frame:self.bounds)
        self.addSubview(lab)
        lab.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        lab.font = UIFont(name: "GillSans-Bold", size: 40)
        lab.text = "Testing"
        self.lab = lab
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

定义UICollectionReusableView子类

通过调用

Register（\ufo:fo），将UICollectionReusableView子类注册到布局中（而不是集合视图）
public class DecorationView : UICollectionReusableView
{
    private static NSString classId = new NSString ("DecorationView");
    public static NSString ClassId { get { return classId; } }

    UIImageView blueMarble;

    [Export("initWithFrame:")]
    public DecorationView (RectangleF frame) : base(frame)
    {
        blueMarble = new UIImageView (UIImage.FromBundle ("bluemarble.png"));

        AddSubview (blueMarble);    
    }
}


public class SimpleCollectionViewController : UICollectionViewController
{
    public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();
        //Register the cell class (code for AnimalCell snipped)
        CollectionView.RegisterClassForCell (typeof(AnimalCell), AnimalCell.ClassId);
        //Register the supplementary view class (code for SideSupplement snipped)
        CollectionView.RegisterClassForSupplementaryView (typeof(SideSupplement), UICollectionElementKindSection.Header, SideSupplement.ClassId);

        //Register the decoration view
        CollectionView.CollectionViewLayout.RegisterClassForDecorationView (typeof(DecorationView), DecorationView.ClassId);
    }

 //...snip...
}

public class LineLayout : UICollectionViewFlowLayout
{
    public override UICollectionViewLayoutAttributes[] LayoutAttributesForElementsInRect (RectangleF rect)
    {
        var array = base.LayoutAttributesForElementsInRect (rect);
        /* 
        ...snip content relating to cell layout...
        */
        //Add decoration view
        var attributesWithDecoration = new List<UICollectionViewLayoutAttributes> (array.Length + 1);
        attributesWithDecoration.AddRange (array);
        var decorationIndexPath = NSIndexPath.FromIndex (0);
        var decorationAttributes = LayoutAttributesForDecorationView (DecorationView.ClassId, decorationIndexPath);
        attributesWithDecoration.Add (decorationAttributes);

        var extended = attributesWithDecoration.ToArray<UICollectionViewLayoutAttributes> ();

        return extended;
    }

    public override UICollectionViewLayoutAttributes LayoutAttributesForDecorationView (NSString kind, NSIndexPath indexPath)
    {
        var layoutAttributes = UICollectionViewLayoutAttributes.CreateForDecorationView (kind, indexPath);
        layoutAttributes.Frame = new RectangleF (0, 0, CollectionView.ContentSize.Width, CollectionView.ContentSize.Height);
        layoutAttributes.ZIndex = -1;
        return layoutAttributes;
    }
//...snip...
}

class MyTitleView : UICollectionReusableView {
    weak var lab : UILabel!
    override init(frame: CGRect) {
        super.init(frame:frame)
        let lab = UILabel(frame:self.bounds)
        self.addSubview(lab)
        lab.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        lab.font = UIFont(name: "GillSans-Bold", size: 40)
        lab.text = "Testing"
        self.lab = lab
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

private let titleKind = "title"
private let titleHeight : CGFloat = 50
private var titleRect : CGRect {
    return CGRect(10,0,200,self.titleHeight)
}
override init() {
    super.init()
    self.register(MyTitleView.self, forDecorationViewOfKind:self.titleKind)
}

override func layoutAttributesForDecorationView(
    ofKind elementKind: String, at indexPath: IndexPath) 
    -> UICollectionViewLayoutAttributes? {
        if elementKind == self.titleKind {
            let atts = UICollectionViewLayoutAttributes(
                forDecorationViewOfKind:self.titleKind, with:indexPath)
            atts.frame = self.titleRect
            return atts
        }
        return nil
}

override func layoutAttributesForElements(in rect: CGRect) 
    -> [UICollectionViewLayoutAttributes]? {
        var arr = super.layoutAttributesForElements(in: rect)!
        if let decatts = self.layoutAttributesForDecorationView(
            ofKind:self.titleKind, at: IndexPath(item: 0, section: 0)) {
                if rect.intersects(decatts.frame) {
                    arr.append(decatts)
                }
        }
        return arr
}

class MyFlowLayout : UICollectionViewFlowLayout {
    var title = ""
    // ...
}

func setUpFlowLayout(_ flow:UICollectionViewFlowLayout) {
    flow.headerReferenceSize = CGSize(50,50)
    flow.sectionInset = UIEdgeInsetsMake(0, 10, 10, 10)
    (flow as? MyFlowLayout)?.title = "States" // *
}

class MyTitleViewLayoutAttributes : UICollectionViewLayoutAttributes {
    var title = ""
}

override func layoutAttributesForDecorationView(
    ofKind elementKind: String, at indexPath: IndexPath) -> 
    UICollectionViewLayoutAttributes? {
        if elementKind == self.titleKind {
            let atts = MyTitleViewLayoutAttributes( // *
                forDecorationViewOfKind:self.titleKind, with:indexPath)
            atts.title = self.title // *
            atts.frame = self.titleRect
            return atts
        }
        return nil
}

class MyTitleView : UICollectionReusableView {
    weak var lab : UILabel!
    // ... the rest as before ...
    override func apply(_ atts: UICollectionViewLayoutAttributes) {
        if let atts = atts as? MyTitleViewLayoutAttributes {
            self.lab.text = atts.title
        }
    }
}