如何使用/不使用UIBezierPath在Swift中循环图像？

Question

I am trying to make an image circulating using UIBezierPath . Here is the code I am using to determine the image's x and y coordinates, its width and its height.

var frm : CGRect = self.image.frame
    let originX = frm.origin.x
    let originY = frm.origin.y
    let originWidth = frm.size.width
    let originHeight = frm.size.height
    self.image.frame = frm

However, if I put originX and originY in this code:

let path = UIBezierPath()
    path.moveToPoint(CGPoint(x: originX+50, y: originY))
    path.addCurveToPoint(CGPoint(x: originX-20, y: originY),
    controlPoint1: CGPoint(x: originX+20, y: originY),
    controlPoint2: CGPoint(x: originX-10, y: originY))

    let anim = CAKeyframeAnimation(keyPath: "position")

    // set the animations path to our bezier curve
    anim.path = path.CGPath

    anim.repeatCount = Float.infinity
    anim.duration = 5.0

    image.layer.addAnimation(anim, forKey: "animate position along path")

The image just stays at the top left of the screen (instead of being placed close to the center). Why? By the way, are there any other ways to make an image circulating other than using UIPathBezier ?

Answer 1

Well, first of all you need to override the UIBezierPath() constructor so you can give parameters as originX and originY , also you must use var instead of let because var is a simple variable and let is a constant and it cannot be modified in Swift.

I dont have Xcode with me but the code should look like this:

override func UIBezierPath(#x:CGFloat, andOriginX:CGFloat) {
}

let path = UIBezierPath(x, y)
    path.moveToPoint(CGPoint(x: x+50, y: y)) // and so one...
    path.addCurveToPoint(CGPoint(x: originX-20, y: originY),
    controlPoint1: CGPoint(x: originX+20, y: originY),
    controlPoint2: CGPoint(x: originX-10, y: originY))

    let anim = CAKeyframeAnimation(keyPath: "position")

    // set the animations path to our bezier curve
    anim.path = path.CGPath

    anim.repeatCount = Float.infinity
    anim.duration = 5.0
    image.layer.addAnimation(anim, forKey: "animate position along path")
)