与"CGRectMake"坐标混淆

Question

从以下代码

// yPos = 0, width = 100, height = 150
[imagesMutable enumerateObjectsUsingBlock: ^(UIScrollView verticalScroll, NSUInteger idx, BOOL *stop){
  [verticalScroll addSubView:[UIImageView setFrame:CGRectMake(0, yPos, width, height)]]
  // some code
  yPos += (height + 15)
}];

比方说,如果imagesMutable得到3个对象.当我从某个地方读到CGRectMake正在使用笛卡尔坐标时(x = 0,y = 0将在左下角).所以,它应该是

[verticalScroll addSubView:[UIImageView setFrame:CGRectMake(0, 0, 100, 150)]]
[verticalScroll addSubView:[UIImageView setFrame:CGRectMake(0, 165, 100, 150)]]
[verticalScroll addSubView:[UIImageView setFrame:CGRectMake(0, 330, 100, 150)]]

这应该意味着

First CGRectMake should has bottom left at (0, 0) and top right at (100, 150)
Second CGRectMake should has bottom left at (0, 165) and top right at (100, 315) 
Third CGRectMake should has bottom left at (0, 330) and top right at (100, 480)

然后,从顶部到底部的图像的顺序应该是3 - > 2 - > 1比较到imagesMutable的对象排序(1 - > 2 - > 3)

但是为什么,它以1 - > 2 - > 3的顺序出现,与我启动应用程序时imagesMutable的对象排序相同？我错过了什么吗？

Answer 1

(0,0)不是左下角,而是左上角.

视图的y坐标反转,因此当您向下移动屏幕时y会增加.