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Animate drawing sine wave. CABasicAnimation and UIBezierPath
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// Draw a sine curve with a fill | |
let centerY = frame.height / 2 // find the vertical center | |
let steps = 200 // Divide the curve into steps | |
let stepX = frame.width / CGFloat(steps) // find the horizontal step distance | |
// Make a path | |
let path = UIBezierPath() | |
path.moveToPoint(CGPoint(x: 0, y: centerY)) | |
// Loop and draw steps in straingt line segments | |
for i in 0...steps { | |
let x = CGFloat(i) * stepX | |
let y = (sin(Double(i) * 0.1) * 40) + Double(centerY) | |
path.addLineToPoint(CGPoint(x: x, y: CGFloat(y))) | |
} | |
pathLayer.path = path.CGPath | |
pathLayer.lineWidth = 3 | |
pathLayer.fillColor = UIColor.clearColor().CGColor | |
pathLayer.strokeColor = UIColor.redColor().CGColor | |
pathLayer.strokeStart = 0 | |
pathLayer.strokeEnd = 0 // << | |
let animation = CABasicAnimation(keyPath: "strokeEnd") | |
animation.fromValue = 0 | |
animation.toValue = 1 | |
animation.duration = 3 | |
pathLayer.addAnimation(animation, forKey: "strokeEnd") |
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