ios 如何在 UIButton 中居中图像而不在 Swift 中双向拉伸？
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How to center an image inside an UIButton without stretching in both direction in Swift?
提问by Ariel
I am making a custom keyboard and I need to centre the image of the shift icon inside the shift button. The image is 100px x 100px.
我正在制作一个自定义键盘，我需要将 shift 按钮内的 shift 图标的图像居中。图像为 100 像素 x 100 像素。
However, the button frame in portrait is 36pt x 38pt, and in landscape, it is 68pt x 32pt. I have tried using button image inset property to centre the image. However, it does not does so.
但是，纵向的按钮框是36pt x 38pt，横向的则是68pt x 32pt。我曾尝试使用按钮图像插入属性来居中图像。然而，它并没有这样做。
I tried myself and set the image edge insets to (25,25,25,25), the image centres in both sizes. However, the icon becomes too small to see.
我尝试了自己并将图像边缘插入设置为(25,25,25,25)，两种尺寸的图像中心。但是，图标变得太小而无法看到。
shiftButton.setImage(UIImage(named: "shift"), forState: .Normal)
shiftButton.imageEdgeInsets = UIEdgeInsetsMake(0,0,0,0)
I am making the button programatically. And, I need the button to scale maintaining its aspect ratio i.e. 1:1. Its maximum width or height is always tied to the button's height itself. The image width/height should be maximum of button's height. And, it should not stretch in any way to distort the icon. However, the button itself can stretch.
我正在以编程方式制作按钮。而且，我需要按钮来缩放保持其纵横比，即1:1. 它的最大宽度或高度始终与按钮本身的高度相关。图像宽度/高度应该是按钮高度的最大值。而且，它不应以任何方式拉伸以扭曲图标。但是，按钮本身可以拉伸。
I need the image to scale according to button frame but maintain its aspect ratio. And, it can down scale or up scale, but should always maintain the 1:1 aspect ratio.
我需要根据按钮框架缩放图像但保持其纵横比。而且，它可以缩小或放大，但应始终保持 1:1 的纵横比。
Any suggestions for solving this problem?
有什么建议可以解决这个问题吗？
回答by Ariel
Finally a solution came through. You must set the content mode for the image inside the UIButton.
终于有办法解决了。您必须为 UIButton 内的图像设置内容模式。
The solution is to update the contentModeof the Imagewhen you are using a foreground image inside a button along with the contentModeof the UIButton.
该解决方案是更新contentMode的Image，当你与一起使用按钮内的前景图像contentMode的UIButton。
shiftButton.contentMode = .Center
shiftButton.imageView?.contentMode = .ScaleAspectFit
回答by Prateep Gedupudi
- Add User Defined Runtime Attributes to your button.
- 将用户定义的运行时属性添加到您的按钮。
In the screen shot below value 1 is equal to scaleAspectFit
在下面的屏幕截图中，值 1 等于 scaleAspectFit
imageView.ContentMode = scaleAspectFit
回答by Scott Zhu
If you're using storyboard, double-check that you don't have anything set for the button title.
如果您使用的是故事板，请仔细检查您没有为按钮标题设置任何内容。
回答by Justin Vallely
I was able to center the image by setting the content insets to 0 using the size inspector on the storyboard:
我能够通过使用情节提要上的大小检查器将内容插入设置为 0 来使图像居中：
回答by Viktor Simkó
Set the button's content mode to Center:
将按钮的内容模式设置为Center：
shiftButton.contentMode = .Center
