swift ios UIButton image title 對齊方式 自定義image圖片的位置

上，下，左 右，通過uibutton 的 imageEdgeInsets ，和 titleEdgeInsets 實現。

//
//  UIButton+Util.swift
//  PetPet
//
//  Created by LiZhi on 2022/8/15.
//

import Foundation
import UIKit

extension UIButton {
    /*
     UIButton默認布局是圖片在左、文字在右，圖片和文字之間邊距為0，圖片和文字整體居中顯示
     當同時存在image和title時，imageEdgeInsets中的top、left、bottom相對于UIButton，right相對于title，同理，titleEdgeInsets中的top、bottom、rright相對于UIButton，left相對于title
     imageEdgeInsets = UIEdgeInsets.init(top: 5, left: 0, bottom: -5, right: 0) 表示圖片整體向下移動5
     imageEdgeInsets = UIEdgeInsets.init(top: -5, left: 4, bottom: 5, right: -4) 表示圖片整體向上移動5，向右移動4
     
     默認的情況下當按鈕比較小時會自動保留圖片的尺寸和將文字部分縮小，一般出現在圖標和文字上下布局，button的整體較小時,因為按鈕總體寬度比較小，導致系統給分配的寬度不足以完整顯示文字
     */
    enum ImagePosition: Int {
        case top = 1
        case left = 2
        case bottom = 3
        case right = 4
    }
    
    /// 設置label相對于圖片的位置
    /// - Parameters:
    ///   - anImage: 按鈕圖片
    ///   - title: 標題
    ///   - imagePosition: label相對于圖片的位置（上下左右）
    ///   - additionalSpacing: 文字和圖片的間隔
    ///   - state: UIControl.State
    ///   - isSureTitleCompress: 是否明確文字被系統擠壓，true：使用文字被壓縮的調整模式，false：根據系統為文字分配的size自動適配（主要是了為了應對有些文字擠壓的按鈕被重復設置的情況）要放到約束之后才會生效
    func setImage(image anImage: UIImage?, title: String, imagePosition: ImagePosition, additionalSpacing: CGFloat, state: UIControl.State = .normal, isSureTitleCompress: Bool = false) {
        self.setImage(anImage, for: state)
        self.setTitle(title, for: state)
        self.positionLabelRespectToImage(title: title, position: imagePosition, spacing: additionalSpacing, isSureTitleCompress: isSureTitleCompress)
    }
    
    private func positionLabelRespectToImage(title: String, position: ImagePosition, spacing: CGFloat, isSureTitleCompress: Bool = false) {
        self.layoutIfNeeded() // 這一步很重要，否則如果UIButton通過約束布局會導致titleRect獲取的rect不準
        let imageSize = self.imageView?.image?.size ?? .zero
        let titleSize = self.titleRect(forContentRect: self.frame).size // 系統為titleLabel分配的size
        
        var titleNeedSize: CGSize = .zero // 展示文字實際所需的size
        if let font = self.titleLabel?.font {
            titleNeedSize = title.size(withAttributes: [NSAttributedString.Key.font: font])
        }
        var isTitleCompress = false // 文字是否被系統壓縮
        if isSureTitleCompress {
            isTitleCompress = true
        } else if titleNeedSize.width > titleSize.width {
            isTitleCompress = true
        }
        
        switch position {
        case .top:
            let imageTop = -(titleSize.height/2 + spacing/2)
            let titleTop = imageSize.height/2 + spacing/2
            if isTitleCompress {
                let imageLeft = (self.bounds.size.width - imageSize.width)/2
                self.imageEdgeInsets = UIEdgeInsets(top: imageTop, left: imageLeft, bottom: -imageTop, right: 0)
                self.titleEdgeInsets = UIEdgeInsets(top: titleTop, left: -imageSize.width, bottom: -titleTop, right: 0)
            } else {
                self.imageEdgeInsets = UIEdgeInsets(top: imageTop, left: titleSize.width/2, bottom: -imageTop, right: -titleSize.width/2)
                self.titleEdgeInsets = UIEdgeInsets(top: titleTop, left: -imageSize.width/2, bottom: -titleTop, right: imageSize.width/2)
            }
            
        case .left:
            self.imageEdgeInsets = UIEdgeInsets(top: 0, left: -spacing/2, bottom: 0, right: spacing/2)
            self.titleEdgeInsets = UIEdgeInsets(top: 0, left: spacing/2, bottom: 0, right: -spacing/2)
            
        case .bottom:
            let imageTop = titleSize.height/2 + spacing/2
            let titleTop = -(imageSize.height/2 + spacing/2)
            if isTitleCompress {
                let imageLeft = (self.bounds.size.width - imageSize.width)/2
                self.imageEdgeInsets = UIEdgeInsets(top: imageTop, left: imageLeft, bottom: -imageTop, right: 0)
                self.titleEdgeInsets = UIEdgeInsets(top: titleTop,
                                                    left: -imageSize.width, bottom: -titleTop, right: 0)
            } else {
                self.imageEdgeInsets = UIEdgeInsets(top: imageTop, left: titleSize.width/2, bottom: -imageTop, right: -titleSize.width/2)
                self.titleEdgeInsets = UIEdgeInsets(top: titleTop,
                                                    left: -imageSize.width/2, bottom: -titleTop, right: imageSize.width/2)
            }
            
        case .right:
            self.imageEdgeInsets = UIEdgeInsets(top: 0, left: titleSize.width + spacing/2, bottom: 0,
                                                right: -(titleSize.width + spacing/2))
            self.titleEdgeInsets = UIEdgeInsets(top: 0, left: -(imageSize.width + spacing/2), bottom: 0, right: imageSize.width + spacing/2)
        }
    }
}