平移视图和旋转视图问题
我有一个自定义的 UIImageView，我可以通过进行翻译来将其拖动到屏幕上（xDif 和 yDif 是手指移动的量）：
CGAffineTransform translate = CGAffineTransformMakeTranslation(xDif, yDif);
[self setTransform: CGAffineTransformConcat([self transform], translate)];
假设我在 x 和 y 方向上将 ImageView 移动了 50px。然后，我尝试旋转 ImageView （通过手势识别器）：
CGAffineTransform transform = CGAffineTransformMakeRotation([recognizer rotation]);
myImageView.transform = transform;
发生的情况是 ImageView 突然移动到 ImageView 最初所在的位置（在平移之前 - 不是从移动的位置 + 50px 在两个方向上）。
（似乎无论我如何翻译视图，ImageView 子类的 self.center 保持不变 - 它最初放置在 IB 中的位置）。
另一个问题是，如果我将 ImageView 旋转 30 度，然后尝试再旋转一点，它会再次从原始位置（角度 = 0）开始并从那里开始，为什么它不从角度开始30 度而不是 0 度。
I have a custom UIImageView, I can drag it around screen by making a translation with (xDif and yDif is the amount fingers moved):
CGAffineTransform translate = CGAffineTransformMakeTranslation(xDif, yDif);
[self setTransform: CGAffineTransformConcat([self transform], translate)];
Let's say I moved the ImageView for 50px in both x and y directions. I then try to rotate the ImageView (via gesture recognizer) with:
CGAffineTransform transform = CGAffineTransformMakeRotation([recognizer rotation]);
myImageView.transform = transform;
What happens is the ImageView suddenly moves to where the ImageView was originally located (before the translation - not from the moved position + 50px in both directions).
(It seems that no matter how I translate the view, the self.center of the ImageView subclass stays the same - where it was originally laid in IB).
Another problem is, if I rotate the ImageView by 30 deg, and then try to rotate it a bit more, it will again start from the original position (angle = 0) and go from there, why wouldn't it start from the angle 30 deg and not 0.
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您正在覆盖之前的转换。要添加到当前变换，您应该这样做 -
由于您要按顺序更改
transform属性，因此您应该使用CGAffineTransformRotate、CGAffineTransformTranslate 和CGAffineTransformScale来代替，以便您添加到原始变换而不是创建新变换。You are overwriting the earlier transform. To add to the current transform, you should do this –
Since you're changing the
transformproperty in a serial order, you should useCGAffineTransformRotate,CGAffineTransformTranslateandCGAffineTransformScaleinstead so that you add to the original transform and not create a new one.