[英]How do I circulate an image in Swift using/without using UIBezierPath?
我正在嘗試使用UIBezierPath
使圖像循環。 這是我用來確定圖像的x
和y
坐標,其寬度和高度的代碼。
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
但是,如果我在此代碼中放入originX
和originY
:
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")
圖像僅停留在屏幕的左上方(而不是靠近中心放置)。 為什么? 順便說一句,除了使用UIPathBezier
之外,還有其他方法可以使圖像循環嗎?
好吧,首先,您需要重寫UIBezierPath()
構造函數,以便可以將參數指定為originX
和originY
,還必須使用var
而不是let
因為var
是一個簡單變量,let是一個constant
,並且不能在Swift中進行修改。
我沒有Xcode,但代碼應如下所示:
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")
)
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