What exactly does CGAffineTransform mean? What does each value mean?

  ios, question
struct CGAffineTransform {
  CGFloat a, b, c, d;
  CGFloat tx, ty;
};

The property of transform of UIView has not been understood very well, and there are no experts to explain it.

CGAffineTransform is actually a matrix

| a,  b,  0 |
| c,  d,  0 |
| tx, ty, 1 |

a={1,1} b={1,2} c={2,1} d={2,2} tx={3,1} ty={3,2}
This matrix is used to mark the changes of this View, which can be rotation, scaling and translation.
In other words, the coordinates of View are {x,y}, and the changed coordinates are {x’,y’}

.
                    | a,  b,  0 |
{x',y',1}={x,y,1} x | c,  d,  0 |
                    | tx, ty, 1 |

http://developer.apple.com/library/io …This is an official document. There are many ways to easily create this matrix.