swift 跑马灯

最近公司项目需要写一个跑马灯的效果，android的直接设置属性就可以了。为啥ios没有呢，我想一定是乔帮主认为跑马灯是个反人类的设计。哈哈，随便扯个蛋，进入正题。实现原理就是使用2个label，一前一后2个label的layer进行平行移动，当后面label的layer移动到前面的位置，动画再复原，重复执行。这样一个基本的跑马灯就实现了，我在此基础上给跑马灯加了，开始，停止，暂停，继续，4个动作。

动画代码

    // MARK: - 跑马灯动画实现过程
    func marqueeAnimation() {
        let frontAnima = CABasicAnimation()
        frontAnima.keyPath = "position"
        frontAnima.fromValue = NSValue(CGPoint: CGPoint(x:  self.frontLabel.frame.width / 2 , y: self.frame.height / 2))
        frontAnima.toValue = NSValue(CGPoint: CGPoint(x: -1 * self.frontLabel.frame.width / 2, y: self.frame.height / 2))
        frontAnima.duration = self.time
        frontAnima.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
        frontAnima.repeatCount = MAXFLOAT
        
        let behindAnima = CABasicAnimation()
        behindAnima.keyPath = "position"
        behindAnima.fromValue = NSValue(CGPoint: CGPoint(x:  self.frontLabel.frame.width / 2 * 3 , y: self.frame.height / 2))
        behindAnima.toValue = NSValue(CGPoint: CGPoint(x:  self.frontLabel.frame.width / 2, y: self.frame.height / 2))
        behindAnima.duration = self.time
        behindAnima.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
        behindAnima.repeatCount = MAXFLOAT
        
        self.frontLabel.layer.addAnimation(frontAnima, forKey: "frontAnima")
        self.behindLabel.layer.addAnimation(behindAnima, forKey: "behindAnima")
    }

开始

   // MARK: - 开始跑马灯动画
    func start(){
        if isRun == false {
            isRun = true
            isSuspend = false
            frontLabel.layer.timeOffset = 0.0
            behindLabel.layer.timeOffset = 0.0
            frontLabel.layer.speed = 1.0
            behindLabel.layer.speed = 1.0
            frontLabel.layer.beginTime = 0.0
            behindLabel.layer.beginTime = 0.0
            marqueeAnimation()
        }
    }
    

停止

    // MARK: - 停止跑马灯动画
    func stop() {
        if isRun {
            isRun = false
            frontLabel.layer.removeAnimationForKey("frontAnima")
            behindLabel.layer.removeAnimationForKey("behindAnima")
        }
    }

暂停

  // MARK: -  暂停动画
    func suspend() {
        if isRun && isSuspend == false {
            isSuspend = true
            
            let frontPauseTime = frontLabel.layer.convertTime(CACurrentMediaTime(), fromLayer: nil)
            frontLabel.layer.speed = 0.0
            frontLabel.layer.timeOffset = frontPauseTime

            let behindPauseTime = behindLabel.layer.convertTime(CACurrentMediaTime(), fromLayer: nil)
            behindLabel.layer.speed = 0.0
            behindLabel.layer.timeOffset = behindPauseTime
            
        }
    }

继续

   // MARK: - 继续动画
    func continuation() {
        if isRun && isSuspend {
            isSuspend = false
            let frontPauseTime = frontLabel.layer.timeOffset
            frontLabel.layer.speed = 1.0
            frontLabel.layer.timeOffset = 0.0
            frontLabel.layer.beginTime = 0.0
            let frontTimeSincePause = frontLabel.layer.convertTime(CACurrentMediaTime(), fromLayer: nil)  - frontPauseTime
            frontLabel.layer.beginTime = frontTimeSincePause
            
            let behindPauseTime = behindLabel.layer.timeOffset
            behindLabel.layer.speed = 1.0
            behindLabel.layer.timeOffset = 0.0
            behindLabel.layer.beginTime = 0.0
            let behindTimeSincePause = behindLabel.layer.convertTime(CACurrentMediaTime(), fromLayer: nil)  - behindPauseTime
            behindLabel.layer.beginTime = behindTimeSincePause
            
        }
    }

总结

上面就是我实现跑马灯的核心代码。在网上找了一番都没有遇到满意的跑马灯代码，就自己写了一份，欢迎大家前来交流。如果是使用oc的，那就需要你自己翻译成oc代码了^_ swift跑马灯代码