Question

我有两个ViewController。

带一个按钮的基本视图控制器，此按钮执行segue（模态化）到TimerViewController
TimerViewController - 此视图控制器为圆圈中的倒计时设置动画。

如果我将TimerViewController设置为初始视图控制器，一切都像魅力，计时器倒计时和圆圈填充红色作为时间倒计时。请参阅屏幕截图：http://i.imgur.com/TiBdUUS.png

但是如果我从第一个View Controller执行segue到TimerViewController圈已经填充了红色。请参阅屏幕截图：http://i.imgur.com/8D0IWiJ.png

我无法理解这段代码有什么问题以及为什么圈子被填满了？这是我的代码：

class TimerViewController: UIViewController {

// View 500x500
@IBOutlet weak var plView: UIView!

// define the time left
let timeLeftShapeLayer = CAShapeLayer()
let bgShapeLayer = CAShapeLayer()
var timeLeft: NSTimeInterval = 60.0
var endTime: NSDate!
var timeLabel =  UILabel()
var timer = NSTimer()

// here you create your basic animation object to animate the strokeEnd
let strokeIt = CABasicAnimation(keyPath: "strokeEnd")


// at viewDidload set the endTime and add your CAShapeLayer to your view:
override func viewDidLoad() {
    super.viewDidLoad()
    plView.backgroundColor = UIColor(white: 0.94, alpha: 1.0)

    drawBgShape()
    drawTimeLeftShape()
    addTimeLabel()

    // here you define the fromValue, toValue and duration of your animation
    strokeIt.fromValue = 0.0
    strokeIt.toValue = 1.0
    strokeIt.duration = 60.0

    // add the animation to your timeLeftShapeLayer
    timeLeftShapeLayer.addAnimation(strokeIt, forKey: nil)

    // define the future end time by adding the timeLeft to now NSDate()
    endTime = NSDate().dateByAddingTimeInterval(timeLeft)
    timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: #selector(TimerViewController.updateTime), userInfo: nil, repeats: true)
}


// define a method to create UIBezierPath
// startAngle at -90˚ and endAngle 270
func drawBgShape() {
    bgShapeLayer.path = UIBezierPath(arcCenter: CGPoint(x: plView.frame.midX , y: plView.frame.midY), radius:
        100, startAngle: -90.degreesToRadians, endAngle: 270.degreesToRadians, clockwise: true).CGPath
    bgShapeLayer.strokeColor = UIColor.whiteColor().CGColor
    bgShapeLayer.fillColor = UIColor.clearColor().CGColor
    bgShapeLayer.lineWidth = 15
    plView.layer.addSublayer(bgShapeLayer)
}
func drawTimeLeftShape() {
    timeLeftShapeLayer.path = UIBezierPath(arcCenter: CGPoint(x: plView.frame.midX , y: plView.frame.midY), radius:
        100, startAngle: -90.degreesToRadians, endAngle: 270.degreesToRadians, clockwise: true).CGPath
    timeLeftShapeLayer.strokeColor = UIColor.redColor().CGColor
    timeLeftShapeLayer.fillColor = UIColor.clearColor().CGColor
    timeLeftShapeLayer.lineWidth = 15
    plView.layer.addSublayer(timeLeftShapeLayer)
}

// add your Label
func addTimeLabel() {
    timeLabel = UILabel(frame: CGRectMake(plView.frame.midX-50 , plView.frame.midY-25, 100, 50))
    timeLabel.textAlignment = .Center
    timeLabel.text = timeLeft.time
    plView.addSubview(timeLabel)
}


// when updating the time
func updateTime() {
    if timeLeft > 0 {
        timeLeft = endTime.timeIntervalSinceNow
        timeLabel.text = timeLeft.time
    } else {
        timeLabel.text = "00:00"
        timer.invalidate()
    }
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

}

}

// extension convert the degrees to radians and display time
extension Double {
var degreesToRadians : CGFloat {
    return CGFloat(self) * CGFloat(M_PI) / 180.0
}
}

extension NSTimeInterval {
var time:String {
    return String(format:"%02d:%02d", Int(self/60.0),        Int(ceil(self%60)) )
}
}

Answer 1

尝试将圈子初始化代码放入viewDidAppear方法而不是viewDidLoad

当我执行segue到ViewController圈已经填充

1 个答案: