另见

CGAffineTransform 参考(文档)
转换(文档)
Swift:翻译和旋转 CGContext，一个视觉解释(iOS/Xcode)
揭开 CGAffineTransform 的神秘面纱

这个答案已经用 Swift 4 测试过

I would like to apply multiple transforms to a UIView (or subclass of UIView), such as translate, rotate, and scale. I know that two transforms can be applied with CGAffineTransformConcat, but how do I do it if I have three or more transforms?

I have seen these questions:

Applying multiple transforms to a UIView / CALayer
Using Multiple CGAffineTransforms On Text Matrix

but these questions are asking something different, and the given answers just talk about applying two transforms with CGAffineTransformConcat. Also, they use Objective-C rather than Swift.

解决方案

You can apply multiple transforms by stacking them on top of each other.

var t = CGAffineTransform.identity
t = t.translatedBy(x: 100, y: 300)
t = t.rotated(by: CGFloat.pi / 4)
t = t.scaledBy(x: -1, y: 2)
// ... add as many as you want, then apply it to to the view
imageView.transform = t

Or more compactly (but not necessarily as readable):

imageView.transform = CGAffineTransform.identity.translatedBy(x: 100, y: 300).rotated(by: CGFloat.pi / 4).scaledBy(x: -1, y: 2)

This series of transforms produces the image on the right:

Thanks to this answer for teaching me how to do it.

Notes

The order in which you apply the transforms matters. For example, if the transforms were done in the opposite order it would produce the following result.
```
t = t.scaledBy(x: -1, y: 2)
t = t.rotated(by: CGFloat.pi / 4)
t = t.translatedBy(x: 100, y: 300)
```

transforms

如何在 Swift 中应用多个转换

问题描述

另见

Notes

See also