如何在 Swift 中旋转 UIButton 和 UILabel 的文本?

问题描述

如何旋转 UIButton 和 UILabel 的文本?90度，180度.

注意:在将其标记为重复之前，我有意将我的问题建模为该问题的 Swift 版本:

的文档

基本格式是 CGAffineTransform(rotationAngle: CGFloat) 其中 rotationAngle 是弧度，而不是度数.

一个完整的圆(360 度)有 2π 弧度.Swift 包含有用的常量 CGFloat.pi.

• CGFloat.pi = π = 180 度
• CGFloat.pi/2 = π/2 = 90 度

自动布局:

自动布局不适用于旋转视图.(有关原因，请参阅 Frame vs Bounds.)这个问题可以通过创建自定义视图来解决.This answer 展示了如何为 UITextView 执行此操作，但对于标签或按钮.(请注意，您必须删除该答案中的 CGAffineTransformScale 行，因为您不需要镜像文本.)

相关

• 如何在 CALayer 上进行转换?
• 如何在 Swift 中应用多个转换
• iOS 中的 CTM 变换与仿射变换(用于平移、旋转、缩放)

How can you rotate text for UIButton and UILabel? 90 degrees, 180 degrees.

Note: Before you mark this as a duplicate, I am intentionally modelling my question as a Swift version of this one: How can you rotate text for UIButton and UILabel in Objective-C?

解决方案

I am putting my answer in a similar format to this answer.

Here is the original label:

Rotate 90 degrees clockwise:

yourLabelName.transform = CGAffineTransform(rotationAngle: CGFloat.pi / 2)

Rotate 180 degrees:

yourLabelName.transform = CGAffineTransform(rotationAngle: CGFloat.pi)

Rotate 90 degrees counterclockwise:

yourLabelName.transform = CGAffineTransform(rotationAngle: -CGFloat.pi / 2)

Do the same thing to rotate a button. Thankfully the touch events also get rotated so the button is still clickable in its new bounds without having to do anything extra.

yourButtonName.transform = CGAffineTransform(rotationAngle: CGFloat.pi / 2)

Notes:

Documentation for CGAffineTransform

The basic format is CGAffineTransform(rotationAngle: CGFloat) where rotationAngle is in radians, not degrees.

There are 2π radians in a full circle (360 degrees). Swift includes the useful constant CGFloat.pi.

• CGFloat.pi = π = 180 degrees
• CGFloat.pi / 2 = π/2 = 90 degrees

Auto Layout:

Auto layout does not work with rotated views. (See Frame vs Bounds for an explanation why.) This problem can be solved by creating a custom view. This answer shows how to do it for a UITextView, but it is the same basic concept for a label or button. (Note that you will have to remove the CGAffineTransformScale line in that answer since you don't need to mirror the text.)

Related

• How to do transforms on a CALayer?
• How to apply multiple transforms in Swift
• CTM transforms vs Affine Transforms in iOS (for translate, rotate, scale)

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