Swift：你如何为UIButton和UILabel旋转文本？ [英] Swift: How can you rotate text for UIButton and UILabel?

问题描述

如何为 UIButton 和 UILabel 旋转文字？ 90度，180度

注意：在将此标记为重复之前，我故意将我的问题建模为此版本的Swift版本：的文档

基本格式是 CGAffineTransform（rotationAngle：CGFloat）其中 rotationAngle 以弧度表示，而不是度数。

整圆（360度）有2π弧度。 Swift包含有用常量 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。 （有关解释原因，请参阅框架与边界。）可以通过创建自定义视图来解决此问题。 此答案显示如何为 UITextView 执行此操作，但它与标签或按钮的基本概念相同。 （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上进行变换？


• 如何在Swift中应用多个变换


• CTM转换与iOS中的仿射变换（用于翻译，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: Objective C: How can you rotate text for UIButton and UILabel?

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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