UIButton: how to center an image and a text using imageEdgeInsets and titleEdgeInsets?

For what it's worth, here's a general solution to positioning the image centered above the text without using any magic numbers. Note that the following code is outdated and you should probably use one of the updated versions below:

// the space between the image and text
CGFloat spacing = 6.0;

// lower the text and push it left so it appears centered 
//  below the image
CGSize imageSize = button.imageView.frame.size;
button.titleEdgeInsets = UIEdgeInsetsMake(
  0.0, - imageSize.width, - (imageSize.height + spacing), 0.0);

// raise the image and push it right so it appears centered
//  above the text
CGSize titleSize = button.titleLabel.frame.size;
button.imageEdgeInsets = UIEdgeInsetsMake(
  - (titleSize.height + spacing), 0.0, 0.0, - titleSize.width);

The following version contains changes to support iOS 7+ that have been recommended in comments below. I haven't tested this code myself, so I'm not sure how well it works or whether it would break if used under previous versions of iOS.

// the space between the image and text
CGFloat spacing = 6.0;

// lower the text and push it left so it appears centered 
//  below the image
CGSize imageSize = button.imageView.image.size;
button.titleEdgeInsets = UIEdgeInsetsMake(
  0.0, - imageSize.width, - (imageSize.height + spacing), 0.0);

// raise the image and push it right so it appears centered
//  above the text
CGSize titleSize = [button.titleLabel.text sizeWithAttributes:@{NSFontAttributeName: button.titleLabel.font}];
button.imageEdgeInsets = UIEdgeInsetsMake(
  - (titleSize.height + spacing), 0.0, 0.0, - titleSize.width);

// increase the content height to avoid clipping
CGFloat edgeOffset = fabsf(titleSize.height - imageSize.height) / 2.0;
button.contentEdgeInsets = UIEdgeInsetsMake(edgeOffset, 0.0, edgeOffset, 0.0);

Swift 5.0 version

extension UIButton {
  func alignVertical(spacing: CGFloat = 6.0) {
    guard let imageSize = imageView?.image?.size,
      let text = titleLabel?.text,
      let font = titleLabel?.font
    else { return }

    titleEdgeInsets = UIEdgeInsets(
      top: 0.0,
      left: -imageSize.width,
      bottom: -(imageSize.height + spacing),
      right: 0.0
    )

    let titleSize = text.size(withAttributes: [.font: font])
    imageEdgeInsets = UIEdgeInsets(
      top: -(titleSize.height + spacing),
      left: 0.0,
      bottom: 0.0,
      right: -titleSize.width
    )

    let edgeOffset = abs(titleSize.height - imageSize.height) / 2.0
    contentEdgeInsets = UIEdgeInsets(
      top: edgeOffset,
      left: 0.0,
      bottom: edgeOffset,
      right: 0.0
    )
  }
}

Found how.

First, configure the text of titleLabel (because of styles, i.e, bold, italic, etc). Then, use setTitleEdgeInsets considering the width of your image:

[button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[button setTitle:title forState:UIControlStateNormal];
[button.titleLabel setFont:[UIFont boldSystemFontOfSize:10.0]];

// Left inset is the negative of image width.
[button setTitleEdgeInsets:UIEdgeInsetsMake(0.0, -image.size.width, -25.0, 0.0)]; 

After that, use setTitleEdgeInsets considering the width of text bounds:

[button setImage:image forState:UIControlStateNormal];

// Right inset is the negative of text bounds width.
[button setImageEdgeInsets:UIEdgeInsetsMake(-15.0, 0.0, 0.0, -button.titleLabel.bounds.size.width)];

Now the image and the text will be centered (in this example, the image appears above the text).

Cheers.

You can do it with this Swift extension, which was based in part on Jesse Crossen's answer:

extension UIButton {
  func centerLabelVerticallyWithPadding(spacing:CGFloat) {
    // update positioning of image and title
    let imageSize = self.imageView.frame.size
    self.titleEdgeInsets = UIEdgeInsets(top:0,
                                        left:-imageSize.width,
                                        bottom:-(imageSize.height + spacing),
                                        right:0)
    let titleSize = self.titleLabel.frame.size
    self.imageEdgeInsets = UIEdgeInsets(top:-(titleSize.height + spacing),
                                        left:0,
                                        bottom: 0,
                                        right:-titleSize.width)

    // reset contentInset, so intrinsicContentSize() is still accurate
    let trueContentSize = CGRectUnion(self.titleLabel.frame, self.imageView.frame).size
    let oldContentSize = self.intrinsicContentSize()
    let heightDelta = trueContentSize.height - oldContentSize.height
    let widthDelta = trueContentSize.width - oldContentSize.width
    self.contentEdgeInsets = UIEdgeInsets(top:heightDelta/2.0,
                                          left:widthDelta/2.0,
                                          bottom:heightDelta/2.0,
                                          right:widthDelta/2.0)
  }
}

This defines a function centerLabelVerticallyWithPadding that sets the title and image insets appropriately.

It also sets the contentEdgeInsets, which I believe is necessary to ensure that intrinsicContentSize still works correctly, which would need to use Auto Layout.

I believe all solutions which subclass UIButton are technically illegitimate, since you are not supposed to subclass UIKit controls. I.e., in theory they might break in future releases.