swift 无法显示 imageview 底部的视图

Question

i'm trying to show a layout at from the bottom of an imageview to a predefined height. Unfortunately its shown at the top, not at the bottom. This is my code i have tried:

   var frm: CGRect = firstImageOverlay.frame
          frm.origin.x = frm.origin.x
          frm.origin.y = frm.origin.y
          frm.size.width = frm.size.width
          frm.size.height = frm.size.height
          firstImageOverlay.frame = frm
              UIView.animate(withDuration: 0.5, animations: {

                self.progressA.frame =   CGRect(x: frm.origin.x, y: frm.origin.y, width: frm.size.width,   height: self.firstImageOverlay.frame.height*CGFloat(0.4))

          })

and here is the result of this code:

the light gray part shows the layout at the left imageview. this should be shown from the bottom till the defined height

Answer 1

iOS uses a reflected cartesian coordinate system with 0,0 in the top right and positive y pointing down and positive x pointing right, so when you draw at x: frm.origin.x, y: frm.origin.y you are saying draw from the top left down to the width and height.

You need to adjust your y coordinate down:

self.progressA.frame = CGRect(x: frm.origin.x, y: frm.origin.y + self.firstImageOverlay.frame.height*CGFloat(0.6), width: frm.size.width,   height: self.firstImageOverlay.frame.height*CGFloat(0.4))