ios 围绕其中心旋转 UIView 保持其大小

Rotate UIView around its center keeping its size

提问by Diego Acosta

I'm trying to rotate an UIViewa few radians but after applying the transformation it doesn't look to be keeping its size. What's the proper way to achieve this?

我正在尝试旋转UIView几个弧度，但在应用转换后，它看起来并没有保持其大小。实现这一目标的正确方法是什么？

Here's what I'm doing and what I get (Blue box with the arrow is the View I'm trying to rotate -- it should keep same aspect as red box behind):

这是我正在做的和我得到的（带箭头的蓝色框是我试图旋转的视图——它应该与后面的红色框保持相同的方面）：

#define DEGREES_TO_RADIANS(angle) ((angle) / 180.0 * M_PI)

double rads = DEGREES_TO_RADIANS(240);
CGAffineTransform transform = CGAffineTransformRotate(CGAffineTransformIdentity, rads);
self.arrowView.transform = transform;

Thanks!

谢谢！

采纳答案by jrturton

You're probably hitting a problem with Autolayout. You probably have constraints on the rotated view pinning it to the edges of the superview. When the transform is applied, Autolayout is updating the view's size to still fit within the superview.

您可能遇到了 Autolayout 的问题。您可能对旋转视图有限制，将其固定到超级视图的边缘。应用转换后，Autolayout 会更新视图的大小以仍然适合超级视图。

You can experiment with different constraints (e.g. pinning the centre of the view to the centre of another view, and pinning the width and height to constant values) or turn Autolayout off for the rotated view, or, if these don't work or don't suit your needs, use a container view which is laid out under Autolayout, and add your rotating view to this, without using Autolayout.

您可以尝试不同的约束（例如将视图的中心固定到另一个视图的中心，并将宽度和高度固定为恒定值）或关闭旋转视图的自动布局，或者，如果这些不起作用或不不适合您的需求，请使用在 Autolayout 下布局的容器视图，并将您的旋转视图添加到其中，而不使用 Autolayout。

This can only be done in code - you can make individual views subject to Autolayout or not by setting translatesAutoresizingMasksIntoConstraintsto NO(Autolayout on) or YES(Autolayout off). You'll need to set the appropriate autoresizing masks if you switch a view from one to the other.

这只能在代码中完成 - 您可以通过设置translatesAutoresizingMasksIntoConstraints为NO(Autolayout on) 或YES(Autolayout off)来使各个视图服从或不服从自动布局。如果从一个视图切换到另一个视图，则需要设置适当的自动调整大小蒙版。

回答by Shaheen Ghiassy

I avoid using macros unless necessary. This works perfectly well

除非必要，我避免使用宏。这很好用

float degrees = 20; //the value in degrees
view.transform = CGAffineTransformMakeRotation(degrees * M_PI/180);

回答by Luca Davanzo

Swift + extensionare your friends!

Swift + 扩展是你的朋友！

// MARK: - UIView Extension -

extension UIView {

    /**
     Rotate a view by specified degrees

     - parameter angle: angle in degrees
     */
    func rotate(angle angle: CGFloat) {
        let radians = angle / 180.0 * CGFloat.pi
        let rotation = CGAffineTransformRotate(self.transform, radians);
        self.transform = rotation
    }

}

In this way, anywhere in your code:

这样，在您的代码中的任何位置：

let view = UIView(frame: CGRectMake(0, 0, 100, 100))
view.backgroundColor = UIcolor.redColor()
view.rotate(angle: 90)

回答by Bill Chan

Update Luca Davanzo's answer with Swift 4:

用 Swift 4 更新 Luca Davanzo 的回答：

/**
 Rotate a view by specified degrees

 - parameter angle: angle in degrees
 */
func rotate(angle: CGFloat) {
    let radians = angle / 180.0 * CGFloat.pi
    let rotation = self.transform.rotated(by: radians)
    self.transform = rotation
}

回答by n00bProgrammer

The CGAffineTransformRotatetransformation rotates from an existing affine transform. The fact that you are using CGAffineTransformIdentitymight be the issue. You must specify the current transform of your view.

在CGAffineTransformRotate从现有的仿射变换旋转变换。您正在使用的事实CGAffineTransformIdentity可能是问题所在。您必须指定视图的当前转换。

#define DEGREES_TO_RADIANS(angle) ((angle) / 180.0 * M_PI)
...
double rads = DEGREES_TO_RADIANS(240);
CGAffineTransform transform = CGAffineTransformRotate(self.arrowView.transform, rads);
self.arrowView.transform = transform;

Also, you might want to consider:

此外，您可能需要考虑：

self.arrowView.transform = CGAffineTransformMakeRotation(rads);

EDIT: If you can, share what you kind of transformation (animated/inanimate , single/iterative) you want to achieve. I believe there might be a better, optimized way of doing this.

编辑：如果可以，请分享您想要实现的转换类型（动画/无生命，单/迭代）。我相信可能有更好的、优化的方法来做到这一点。

回答by Abhinav

Try with this code:

尝试使用此代码：

#define DEGREES_TO_RADIANS(angle) ((angle) / 180.0 * M_PI)

double rads = DEGREES_TO_RADIANS(240);
self.arrowView.layer.transform = CATransform3DMakeRotation(rads, 0, 0, 1);

回答by Sunkas

Swift 5:

斯威夫特 5：

extension UIView {
    func setTransformRotation(toDegrees angleInDegrees: CGFloat) {
        let angleInRadians = angleInDegrees / 180.0 * CGFloat.pi
        let rotation = self.transform.rotated(by: angleInRadians)
        self.transform = rotation
    }
}

回答by Bruno Delgado

On Swift 3:

在 Swift 3 上：

let degrees: CGFloat = -90
let radians = CGFloat(__sinpi(degrees.native/180.0))
view.transform = CGAffineTransform(rotationAngle: radians)

I'm using -90because of this specific part of the documentation about the rotationAngleyou have to pass to CGAffineTransform:

我正在使用-90是因为有关rotationAngle您必须传递给的文档的这一特定部分CGAffineTransform：

The angle, in radians, by which this matrix rotates the coordinate system axes. In iOS, a positive value specifies counterclockwise rotation and a negative value specifies clockwise rotation.

此矩阵旋转坐标系轴的角度（以弧度为单位）。在 iOS 中，正值指定逆时针旋转，负值指定顺时针旋转。

回答by Mike

To my mind you need to calculate the center of your triangle and rotate around this point. Now you rotate the arrow around the center of your square.

在我看来，您需要计算三角形的中心并围绕该点旋转。现在您围绕正方形的中心旋转箭头。

See: One step affine transform for rotation around a point?

请参阅：绕点旋转的一步仿射变换？

I Hope it will help you.

我希望它会帮助你。