iOS CAEmitterLayer 实现粒子发射动画效果

iOS CAEmitterLayer 实现粒子发射动画效果

效果图

代码已上传 GitHub：https://github.com/Silence-GitHub/CoreAnimationDemo

动画效果用 CAEmitterLayer 实现。CAEmitterLayer 显示粒子发射动画，具体的粒子由 CAEmitterCell 封装。代码示例是展示 CAEmitterLayer 如何使用。为了方便，直接在控制器(UIViewController)中设置 CAEmitterLayer。如果在项目中使用，有时在自定义视图(UIView)中加入 CAEmitterLayer 比较合理，例如自定义点赞按钮，可以精简控制器的代码。

下雨动画效果

这里的雨匀速下落，雨的密度逐渐变化。

给控制器添加类型为 CAEmitterLayer 的属性 rainLayer，在 viewDidLoad 方法中对此属性进行初始化

private var rainLayer: CAEmitterLayer!

private func setupRainLayer() {
	// 粒子发射图层
	rainLayer = CAEmitterLayer()
	// 发射器形状为线形，默认发射方向向上
	rainLayer.emitterShape = kCAEmitterLayerLine
	// 从发射器的轮廓发射粒子
	rainLayer.emitterMode = kCAEmitterLayerOutline
	// 优先渲染旧的粒子
	rainLayer.renderMode = kCAEmitterLayerOldestFirst
	// 发射位置
	// 对于线形发射器，线的两端点分别为
	// (emitterPosition.x - emitterSize.width/2, emitterPosition.y, emitterZPosition)和
	// (emitterPosition.x + emitterSize.width/2, emitterPosition.y, emitterZPosition)
	rainLayer.emitterPosition = CGPoint(x: view.bounds.midX, y: 0)
	// 发射器大小
	rainLayer.emitterSize = CGSize(width: view.bounds.width, height: 0)
	// 粒子生成速率的倍数，一开始不发射，设置为零
	rainLayer.birthRate = 0
	
	// 发射的粒子
	let cell = CAEmitterCell()
	// 粒子显示的内容，设置CGImage，显示图片
	cell.contents = #imageLiteral(resourceName: "Heart_red").cgImage
	// 粒子缩放倍数
	cell.scale = 0.1
	// 粒子寿命，单位是秒
	cell.lifetime = 5
	// 粒子生成速率，单位是个/秒，实际显示效果要乘以CAEmitterLayer的birthRate
	cell.birthRate = 1000
	// 粒子速度
	cell.velocity = 500
	// 粒子发射角度，正值表示顺时针方向
	cell.emissionLongitude = CGFloat.pi
	
	// 图层要发射1种粒子
	rainLayer.emitterCells = [cell]
	// 添加粒子发射图层
	view.layer.addSublayer(rainLayer)
}

点击按钮开始或停止动画。用 CABasicAnimation 使粒子生成速率的倍数渐变，达到雨逐渐变大或变小的效果

@IBAction func rainButtonClicked(_ sender: UIButton) {
	// 连续调用此方法会影响雨变大或变小的连贯性，所以禁止连续点击按钮
	sender.isUserInteractionEnabled = false
	// 	粒子生成速率渐变动画
	let birthRateAnimation = CABasicAnimation(keyPath: "birthRate")
	birthRateAnimation.duration = 3
	if rainLayer.birthRate == 0 {
		// 雨变大
		birthRateAnimation.fromValue = 0
		birthRateAnimation.toValue = 1
        rainLayer.birthRate = 1
    } else {
    	// 雨变小
        birthRateAnimation.fromValue = 1
        birthRateAnimation.toValue = 0
        rainLayer.birthRate = 0
    }
    // 加入动画
    rainLayer.add(birthRateAnimation, forKey: "birthRate")
    // 动画时长过后恢复按钮可点击状态
    DispatchQueue.main.asyncAfter(deadline: .now() + birthRateAnimation.duration) { [weak self] in
        guard self != nil else { return }
        sender.isUserInteractionEnabled = true
    }
}

发射一圈粒子动画效果

给控制器添加类型为 CAEmitterLayer 的属性 centerHeartLayer，在 viewDidLoad 方法中对此属性进行初始化

private var centerHeartLayer: CAEmitterLayer!

private func setupCenterHeartLayer() {
	centerHeartLayer = CAEmitterLayer()
	// 发射器形状为圆形，默认向四周发射粒子
	centerHeartLayer.emitterShape = kCAEmitterLayerCircle
	centerHeartLayer.emitterMode = kCAEmitterLayerOutline
	centerHeartLayer.renderMode = kCAEmitterLayerOldestFirst
	// 发射器位置
	// 对于圆形发射器
	// 圆心位于(emitterPosition.x, emitterPosition.y, emitterZPosition)
	// 半径为emitterSize.width
	centerHeartLayer.emitterPosition = CGPoint(x: view.bounds.midX, y: view.bounds.midY)
	centerHeartLayer.emitterSize = centerHeartButton.frame.size
	centerHeartLayer.birthRate = 0
	
	let cell = CAEmitterCell()
	cell.contents = #imageLiteral(resourceName: "Heart_red").cgImage
	cell.lifetime = 1
	cell.birthRate = 2000
	cell.scale = 0.05
	// 粒子缩放倍数每秒减小0.02，粒子逐渐缩小
	cell.scaleSpeed = -0.02
	// 粒子透明度每秒减小1，粒子逐渐变透明
	cell.alphaSpeed = -1
	cell.velocity = 30
	
	centerHeartLayer.emitterCells = [cell]
	view.layer.addSublayer(centerHeartLayer)
}

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)
}

点击按钮开始动画

@IBAction func rightHeartButtonClicked(_ sender: UIButton) {
	sender.isUserInteractionEnabled = false
	// 1秒发射5个粒子，0.2秒发射1个粒子，从上0.2秒开始动画，使按钮点击后立即发射粒子
	rightHeartLayer.beginTime = CACurrentMediaTime() - 0.2
	rightHeartLayer.birthRate = 1
	DispatchQueue.main.asyncAfter(deadline: .now() + 0.8) { [weak self] in
		guard let strongSelf = self else { return }
		strongSelf.rightHeartLayer.birthRate = 0
	}
	DispatchQueue.main.asyncAfter(deadline: .now() + 1.6) { [weak self] in
		guard self != nil else { return }
		sender.isUserInteractionEnabled = true
	}
}

抛物线粒子动画效果

实现抛物线动画需要给粒子加上重力加速度。此外，这里还加入粒子旋转效果，同时发射两种粒子。

给控制器添加类型为 CAEmitterLayer 的属性 gravityLayer，在 viewDidLoad 方法中对此属性进行初始化

private var gravityLayer: CAEmitterLayer!

private func setupGravityLayer() {
	gravityLayer = CAEmitterLayer()
	gravityLayer.renderMode = kCAEmitterLayerOldestFirst
	gravityLayer.emitterPosition = CGPoint(x: 0, y: view.bounds.maxY)
	gravityLayer.birthRate = 0
	
	let cell = CAEmitterCell()
	cell.contents = #imageLiteral(resourceName: "Heart_red").cgImage
	cell.scale = 0.5
	cell.lifetime = 10
	cell.alphaSpeed = -0.1
	cell.birthRate = 10
	cell.velocity = 100
	// y轴方法的加速度，模拟重力加速度
	cell.yAcceleration = 20
	cell.emissionLongitude = -CGFloat.pi / 4
	cell.emissionRange = CGFloat.pi / 4
	// 粒子旋转角速度，单位是弧度/秒，正值表示顺时针旋转
	// 这句可以省略，默认值是零
	cell.spin = 0
	// 粒子旋转角速度变化范围
	cell.spinRange = CGFloat.pi * 2
	
	let cell2 = CAEmitterCell()
	cell2.contents = #imageLiteral(resourceName: "Heart_blue").cgImage
	cell2.scale = 0.3
	cell2.lifetime = 20
	cell2.alphaSpeed = -0.05
	cell2.birthRate = 5
	cell2.velocity = 135
	cell2.yAcceleration = 20
	cell2.emissionLongitude = -CGFloat.pi / 4
	cell2.emissionRange = CGFloat.pi / 4
	cell2.spin = 0
	cell2.spinRange = CGFloat.pi * 2
	
	// 图层要发射2种粒子
	gravityLayer.emitterCells = [cell, cell2]
	view.layer.addSublayer(gravityLayer)
}

点击开始或停止动画

@IBAction func gravityButtonClicked(_ sender: UIButton) {
	if gravityLayer.birthRate == 0 {
		gravityLayer.beginTime = CACurrentMediaTime()
		gravityLayer.birthRate = 1
	} else {
		gravityLayer.birthRate = 0
	}
}

以上是动画的实现方法，代码已上传 GitHub：https://github.com/Silence-GitHub/CoreAnimationDemo

转载请注明出处：http://www.cnblogs.com/silence-cnblogs/p/6971533.html