UIButton that align image and title vertically considering edge insets and content alignment.

VerticalContentButton.swift

//
//  VerticalContentButton.swift
//
//  Created by Roman Filippov on 10.11.2021.
//  Copyright © 2021 com.its. All rights reserved.
//

import UIKit

/// Allign image and title vertically considering edge insets and content aligment
public class VerticalContentButton: UIButton {
    
    public var imageSize: CGSize?
    
    public override func layoutSubviews() {
        super.layoutSubviews()
        
        guard bounds != .zero,
              let imageView = imageView,
              let image = imageView.image,
              let titleLabel = titleLabel else {
            return
        }
        
        let imageSize = self.imageSize ?? image.size

        let minTitleY = contentEdgeInsets.top + imageEdgeInsets.verticalSize() + titleEdgeInsets.top
        let maxTitleWidth = bounds.width - contentEdgeInsets.verticalSize() - titleEdgeInsets.verticalSize()
        let maxTitleHeight = bounds.height - contentEdgeInsets.bottom - titleEdgeInsets.bottom - minTitleY
        let titleSize = titleLabel.sizeThatFits(CGSize(width: maxTitleWidth, height: maxTitleHeight))
        
        let contentSize = CGSize(
            width: imageSize.width + imageEdgeInsets.horizontalSize()
                + titleSize.width + titleEdgeInsets.horizontalSize(),
            height: imageSize.height + imageEdgeInsets.verticalSize()
                + titleSize.height + titleEdgeInsets.verticalSize()
        )
                
        if let imageSize = self.imageSize {
            imageView.bounds.size = imageSize
        } else {
            imageView.sizeToFit()
        }
        titleLabel.bounds.size = titleSize
        
        let setContentVerticalCenter: (CGFloat)->Void = {
            imageView.frame.origin.y = $0 - self.imageEdgeInsets.bottom - imageView.frame.height
            titleLabel.frame.origin.y = $0 + self.titleEdgeInsets.top
        }
        switch contentVerticalAlignment {
        case .center:
            let availableSpaces = bounds.height - contentEdgeInsets.verticalSize() - contentSize.height
            setContentVerticalCenter(contentEdgeInsets.top + availableSpaces / 2 + imageView.bounds.height + imageEdgeInsets.verticalSize())
        case .top:
            setContentVerticalCenter(contentEdgeInsets.top + imageEdgeInsets.verticalSize() + imageSize.height)
        case .bottom:
            setContentVerticalCenter(bounds.height - contentEdgeInsets.bottom + titleEdgeInsets.verticalSize() + titleSize.height)
        case .fill:
            // image.bottom and title.top will be in the center of button
            setContentVerticalCenter((bounds.height - contentEdgeInsets.verticalSize()) / 2 + contentEdgeInsets.top)
        @unknown default:
            assertionFailure()
        }
        
        switch contentHorizontalAlignment {
        case .center:
            let contentCenter = (bounds.width - contentEdgeInsets.horizontalSize()) / 2 + contentEdgeInsets.left
            imageView.frame.origin.x = contentCenter - imageView.bounds.midX
            titleLabel.frame.origin.x = contentCenter - titleLabel.bounds.midX
        case .right, .trailing:
            imageView.frame.origin.x = contentEdgeInsets.right + imageEdgeInsets.right
            titleLabel.frame.origin.x = contentEdgeInsets.right + titleEdgeInsets.right
        case .fill:
            imageView.frame.size.width = contentSize.width - imageEdgeInsets.horizontalSize()
            titleLabel.frame.size.width = contentSize.width - titleEdgeInsets.horizontalSize()
            fallthrough // to allign on left edge
        case .left, .leading:
            imageView.frame.origin.x = contentEdgeInsets.left + imageEdgeInsets.left
            titleLabel.frame.origin.x = contentEdgeInsets.left + titleEdgeInsets.left
        @unknown default:
            assertionFailure()
        }
        
    }
    
    public override var intrinsicContentSize: CGSize {
        guard var imageSize = imageSize ?? imageView?.image?.size,
              var titleSize = titleLabel?.sizeThatFits(CGSize(
                width: CGFloat.greatestFiniteMagnitude,
                height: CGFloat.greatestFiniteMagnitude)) else {
            return super.intrinsicContentSize
        }
        
        imageSize.width += imageEdgeInsets.verticalSize() + contentEdgeInsets.verticalSize()
        imageSize.height += imageEdgeInsets.horizontalSize() + contentEdgeInsets.horizontalSize()
        
        titleSize.width += titleEdgeInsets.verticalSize() + contentEdgeInsets.verticalSize()
        titleSize.height += titleEdgeInsets.horizontalSize() + contentEdgeInsets.horizontalSize()

        return CGSize(
            width: max(imageSize.width, titleSize.width),
            height: max(imageSize.height, titleSize.height)
        )
    }
}

extension UIEdgeInsets {
    
    fileprivate func verticalSize() -> CGFloat {
        return top + bottom
    }
    
    fileprivate func horizontalSize() -> CGFloat {
        return left + right
    }
    
}