点击按钮开始动画
@IBAction func centerHeartButtonClicked(_ sender: UIButton) {
sender.isUserInteractionEnabled = false
// 设置动画开始时间，否则会有太多粒子
centerHeartLayer.beginTime = CACurrentMediaTime()
// 开始生成粒子
centerHeartLayer.birthRate = 1
// 一段时间后停止生成粒子
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
guard let strongSelf = self else { return }
strongSelf.centerHeartLayer.birthRate = 0
}
DispatchQueue.main.asyncAfter(deadline: .now() + 1) { [weak self] in
guard self != nil else { return }
sender.isUserInteractionEnabled = true
}
}
向上发射一个粒子动画效果
给控制器添加类型为 CAEmitterLayer 的属性 leftHeartLayer，在 viewDidLoad 方法中对此属性进行初始化
private var leftHeartLayer: CAEmitterLayer!
private func setupLeftHeartLayer() {
leftHeartLayer = CAEmitterLayer()
// 点状发射器，默认发射方向向右
// 这句可以省略，点状是默认值
leftHeartLayer.emitterShape = kCAEmitterLayerPoint
// 从发射器中的一点发射粒子
// 这句可以省略，是默认值
leftHeartLayer.emitterMode = kCAEmitterLayerVolume
leftHeartLayer.renderMode = kCAEmitterLayerOldestFirst
// 发射器位置
// 对于点状发射器，发射点在(emitterPosition.x, emitterPosition.y, emitterZPosition)
leftHeartLayer.emitterPosition = CGPoint(x: view.bounds.midX * 0.5, y: view.bounds.midY)
leftHeartLayer.birthRate = 0
let cell = CAEmitterCell()
cell.contents = #imageLiteral(resourceName: "Heart_red").cgImage
cell.scale = 0.5
cell.lifetime = 1
// 1秒发射1个粒子
cell.birthRate = 1
cell.alphaSpeed = -1
cell.velocity = 50
cell.emissionLongitude = -CGFloat.pi / 2
leftHeartLayer.emitterCells = [cell]
view.layer.addSublayer(leftHeartLayer)
}
点击按钮开始动画
@IBAction func leftHeartButtonClicked(_ sender: UIButton) {
sender.isUserInteractionEnabled = false
// 从上1秒开始动画，使按钮点击后立即发射粒子
leftHeartLayer.beginTime = CACurrentMediaTime() - 1
leftHeartLayer.birthRate = 1
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
guard let strongSelf = self else { return }
strongSelf.leftHeartLayer.birthRate = 0
}
DispatchQueue.main.asyncAfter(deadline: .now() + 1) { [weak self] in
guard self != nil else { return }
sender.isUserInteractionEnabled = true
}
}
向上发射几个粒子动画效果
给控制器添加类型为 CAEmitterLayer 的属性 rightHeartLayer，在 viewDidLoad 方法中对此属性进行初始化
private var rightHeartLayer: CAEmitterLayer!
private func setupRightHeartLayer() {
rightHeartLayer = CAEmitterLayer()
rightHeartLayer.renderMode = kCAEmitterLayerOldestFirst
rightHeartLayer.emitterPosition = CGPoint(x: view.bounds.midX * 1.5, y: view.bounds.midY)
rightHeartLayer.birthRate = 0
let cell = CAEmitterCell()
cell.contents = #imageLiteral(resourceName: "Heart_red").cgImage
cell.scale = 0.5
cell.lifetime = 1
cell.birthRate = 5
cell.alphaSpeed = -1
cell.velocity = 50
cell.emissionLongitude = -CGFloat.pi / 2
// 粒子发射角度的变化范围
cell.emissionRange = CGFloat.pi / 4
rightHeartLayer.emitterCells = [cell]
view.layer.addSublayer(rightHeartLayer)
}
