结论

// 把redView坐标系上的点greenViewOrigin转换为blueView的坐标系上的点为point
let point = redView.convert(greenViewOrigin, to: blueView)

// 把blueView坐标系上的点greenViewOrigin转换为redView的坐标系上的点为point1
let point1 = redView.convert(greenViewOrigin, from: blueView)

	func convert(:to: ) -> CGPoint	func convert(: from:) -> CGPoint
view为redView的子视图	let result = point - view.frame.origin	let result = point + view.frame.origin
view不为redView的子视图	let result = point + redView.frame.origin - view.frame.origin	let result = point - redView.frame.origin + view.frame.origin

绿色视图和蓝色视图为红色视图的子视图

       // 把redView上的点greenViewOrigin相对blueView结果为
       let point = redView.convert(greenViewOrigin, to: blueView)
       print("point=\(point)")

        // 把blueView上的点greenViewOrigin相对redView结果为
       let point1 = redView.convert(greenViewOrigin, from: blueView)
       print("point1=\(point1)")

       let point2 = redView.convert(blueViewOrigin, to: greenView)
       print("point2=\(point2)")

       let point3 = redView.convert(blueViewOrigin, from: greenView)
       print("point3=\(point3)")
       
       print("\n\n\n\n\n")
       
       let rect = redView.convert(greenView.frame, to: blueView)
       print("rect=\(rect)")
       
       let rect1 = redView.convert(greenView.frame, from: blueView)
       print("rect1=\(rect1)")

输出

屏幕快照 2017-01-16 下午5.42.51.png

func convert(_ rect: CGRect, to view: UIView?) -> CGRect
同
func convert(_ point: CGPoint, to view: UIView?) -> CGPoint
原rect的宽高不变

func convert(_ rect: CGRect, from view: UIView?) -> CGRect
同
func convert(_ point: CGPoint, from view: UIView?) -> CGPoint
原rect的宽高不变

注意

以上方法中view为空时相对keywindow