iOS自定义UIButton缩放setImage向下不起作用

Question

I have problem in scale down setImage size if I add UIButton by programmatically whereas if I add the UIButton by storyboard, the UIButton size remain correctly. The Image is 128x128, I want to shrink down to 30x30

Top one is created from using storyboard, Bottom is created from using programmatically

These are the methods I tried, none able to shrink the image...

let checkBox = UIButton(type .system) 
checkBox.sizeThatFits(CGSize(width: 30, height: 30))
checkBox.contentMode = .scaleAspectFit
checkBox.contentVerticalAlignment = .fill
checkBox.contentHorizontalAlignment = .fill
checkBox.heightAnchor.constraint(equalToConstant: 15.0)
checkBox.widthAnchor.constraint(equalToConstant: 15.0)     

Image is set/update on runtime checkBox.setImage(UImage, for: .normal)

With suggest using checkBox.frame.size.width, checkBox.frame.size.height the image becomes correct size but the UIButton now have extra space. Like the image below. I update image on touchUP UIButton

Answer 1

What about this:

checkBox.frame.size.width = 30
checkBox.frame.size.height = 30

Answer 2

The Image is 128x128, I want to shrink down to 30x30

One obvious solution, in that case, is to shrink the image . Redraw the image into a 30x30 graphics context at 30x30 size and extract the resulting image. Now you have a 30x30 image. That's the best way; it is a waste of memory to hand the runtime a way oversized image and ask it to display it smaller.

Now, if you want to use constraints to size and position the button, that's fine, but you are not doing that correctly. First, you have forgotten to set the button's translatesAutoresizingMaskIntoConstraints to false . Second, you have to supply enough constraints not only to set the button's height and width but also its horizontal and vertical position.