重用UICollectionViewCell会覆盖其drawRects

Question

我有一个collectionView，显示CardCells中带有CardLayout的不同卡片。

每个细胞应显示某种颜色的形状。它永远不应该显示多种颜色。

当我向下滚动时向上滚动，我看到多个颜色重叠。我想这是因为出队了。我尝试在clear:frame和CGContext func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { let c = collectionView.dequeueReusableCell(withReuseIdentifier: "card", for: indexPath) as! CardCell c.card = deck.active[indexPath.row] c.cardLayout = cardLayout c.setNeedsDisplay() return c } class CardCell: UICollectionViewCell { var card = Card() var cardLayout = CardLayout() override init(frame: CGRect) { super.init(frame: frame) layer.borderColor = UIColor.white.cgColor layer.borderWidth = 2 } required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder) } func getCenter() -> CGPoint { return CGPoint(x: frame.size.width / 2, y: frame.size.height / 2) } override func draw(_ rect: CGRect) { let c = UIGraphicsGetCurrentContext(); cardLayout.render(c: c!, card: card, frame: frame) } } class CardLayout: NSObject { func color(i: Int) -> UIColor { return [1: UIColor.red, 2: UIColor.green, 4: UIColor.blue][i]! } func getCenter(frame: CGRect) -> CGPoint { return CGPoint(x: frame.size.width / 2, y: frame.size.height / 2) } func quantity(i: Int) -> Int { return [1: 1, 2: 2, 4: 3][i]! } func loadPath(c: CGContext, card: Card) { if card.fill == 1 { c.setFillColor(color(i: card.color).cgColor) } else { c.setStrokeColor(color(i: card.color).cgColor) } } func drawPath(c: CGContext, card: Card) { if card.fill == 1 { c.fillPath() } else { c.strokePath() } } func render1(c: CGContext, card: Card, frame: CGRect, y: CGFloat) { c.addArc(center: CGPoint(x: frame.size.width / 2, y: y) , radius: frame.size.width / 10, startAngle: 0, endAngle: 360 * 3.142 / 180, clockwise: true) } func render2(c: CGContext, card: Card, frame: CGRect, y: CGFloat) { let m = frame.size.width / 2 let size = CGFloat(10) c.move(to: CGPoint(x: m, y: y - size)) c.addLine(to: CGPoint(x: m - size, y: y + size)) c.addLine(to: CGPoint(x: m + size, y: y + size)) c.addLine(to: CGPoint(x: m, y: y - size)) } func render3(c: CGContext, card: Card, frame: CGRect, y: CGFloat) { } func render(c: CGContext, card: Card, frame: CGRect) { let size = frame.size.height / 6 var num = quantity(i: card.quantity) var sy = size if num == 1 { sy = frame.size.height / 2 } else if num == 2 { sy = (frame.size.height / 2) - (size * 0.5) } else if num == 3 { sy = (frame.size.height / 2) - size } while num > 0 { c.beginPath() c.addRect(frame) c.setFillColor(UIColor.black.cgColor) c.fillPath() c.beginPath() loadPath(c: c, card: card) if card.shape == 1 { render1(c: c, card: card, frame: frame, y: sy) } else if card.shape == 2 { render2(c: c, card: card, frame: frame, y: sy) } else if card.shape == 3 { // render3(c: c, card: card, frame: frame, y: sy) } drawPath(c: c, card: card) num = num - 1 sy = sy + size } } } 的矩形上绘画，两者都没有（明显的）效果。

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