Question

我已经设置并定位了CAEmitterLayer。它显示来自发射器的图像。

代码效果很好，但我有一个问题。我想在5秒后调用snowDribbbleBalls（）函数。我感谢任何帮助我解决问题。

（而不是删除子图层，我想简单地停止功能。）

//real code
class CompletedViewController: UIViewController {

                               self.snowDribbbleBalls()
            DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(5)) { [weak self] in
                cell.birthRate = 0
                cell2.birthRate = 0
                cell3.birthRate = 0
                cell4.birthRate = 0

            }


}

func snowDribbbleBalls() {

        let emitter = Emitter.get(with: #imageLiteral(resourceName: "ichi"))
        emitter.emitterPosition = CGPoint(x: view.frame.width / 2, y: 0)
        emitter.emitterSize = CGSize(width: view.frame.width, height: 2)
        self.view.layer.addSublayer(emitter)

        let emitter2 = Emitter.get(with: #imageLiteral(resourceName: "ni"))
        emitter2.emitterPosition = CGPoint(x: view.frame.width / 6, y: 0)
        emitter2.emitterSize = CGSize(width: view.frame.width, height: 2)
        self.view.layer.addSublayer(emitter2)

        let emitter3 = Emitter.get(with: #imageLiteral(resourceName: "san"))
        emitter3.emitterPosition = CGPoint(x: view.frame.width / 1, y: 0)
        emitter3.emitterSize = CGSize(width: view.frame.width, height: 2)
        self.view.layer.addSublayer(emitter3)

        let emitter4 = Emitter.get(with: #imageLiteral(resourceName: "yon"))
        emitter4.emitterPosition = CGPoint(x: view.frame.width / 3.5, y: 0)
        emitter4.emitterSize = CGSize(width: view.frame.width, height: 2)
        self.view.layer.addSublayer(emitter3)
    }



class Emitter {
    static func get(with image: UIImage) -> CAEmitterLayer {
        let emitter = CAEmitterLayer()
        emitter.emitterShape = kCAEmitterLayerLine
        emitter.emitterCells = generateEmitterCells(with: image)

        let emitter2 = CAEmitterLayer()
        emitter2.emitterShape = kCAEmitterLayerLine
        emitter2.emitterCells = generateEmitterCells(with: image)

        let emitter3 = CAEmitterLayer()
        emitter3.emitterShape = kCAEmitterLayerLine
        emitter3.emitterCells = generateEmitterCells(with: image)

        let emitter4 = CAEmitterLayer()
        emitter4.emitterShape = kCAEmitterLayerLine
        emitter4.emitterCells = generateEmitterCells(with: image)

        return emitter
    }

    static func generateEmitterCells(with image: UIImage) -> [CAEmitterCell] {
        var cells = [CAEmitterCell]()

        let cell = CAEmitterCell()
        cell.contents = image.cgImage
        cell.birthRate = 30
        cell.lifetime = 50
        cell.velocity = CGFloat(300)
        cell.emissionLongitude = (180 * (.pi/180))
        cell.emissionRange = (14 * (.pi/180))
        cell.scale = 0.25
        cell.scaleRange = 0.3
        ////
        let cell2 = CAEmitterCell()
        cell2.contents = image.cgImage
        cell2.birthRate = 26
        cell2.lifetime = 50
        cell2.velocity = CGFloat(160)
        cell2.emissionLongitude = (180 * (.pi/180))
        cell2.emissionRange = (12 * (.pi/180))
        cell2.scale = 0.25
        cell2.scaleRange = 0.2
        ////
        let cell3 = CAEmitterCell()
        cell3.contents = image.cgImage
        cell3.birthRate = 20
        cell3.lifetime = 50
        cell3.velocity = CGFloat(160)
        cell3.emissionLongitude = (180 * (.pi/180))
        cell3.emissionRange = (16 * (.pi/180))
        cell3.scale = 0.25
        cell3.scaleRange = 0.2
        ////
        let cell4 = CAEmitterCell()
        cell4.contents = image.cgImage
        cell4.birthRate = 27
        cell4.lifetime = 20
        cell4.velocity = CGFloat(260)
        cell4.emissionLongitude = (180 * (.pi/180))
        cell4.emissionRange = (10 * (.pi/180))
        cell4.scale = 0.25
        cell4.scaleRange = 0.2

        cells.append(cell)

        return cells

    }

}

Answer 1

只是为了清楚......当图层发光时，该功能没有“运行”，所以真正的问题是“如何阻止发射器？”以及这个问题的答案是通过将发射器层的birthRate设置为零。

所以只需持有一个引用（因为你不想被删除）并在5秒后将birthRate设置为零......

类似的东西：

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(5)) { [weak self] in
    // self.emitter is declared as
    // var emitter: CAEmitterLayer!
    // and set on `emitter = Emitter.get(with: #imageLiteral(resourceName: "ichi"))`
    self?.emitter.birthRate = 0
}

在secods之后停止功能

1 个答案: