把@Piotr的答案变成了一个Swift扩展。请确保在调用此函数之前设置好图像和标题，以便按钮大小适当。

 extension UIButton {
    
    /// Makes the ``imageView`` appear just to the right of the ``titleLabel``.
    func alignImageRight() {
        if let titleLabel = self.titleLabel, imageView = self.imageView {
            // Force the label and image to resize.
            titleLabel.sizeToFit()
            imageView.sizeToFit()
            imageView.contentMode = .ScaleAspectFit
            
            // Set the insets so that the title appears to the left and the image appears to the right. 
            // Make the image appear slightly off the top/bottom edges of the button.
            self.titleEdgeInsets = UIEdgeInsets(top: 0, left: -1 * imageView.frame.size.width,
                bottom: 0, right: imageView.frame.size.width)
            self.imageEdgeInsets = UIEdgeInsets(top: 4, left: titleLabel.frame.size.width,
                bottom: 4, right: -1 * titleLabel.frame.size.width)
          }
        }
     }

这里是解决方案的UIButton与中心对齐的内容。 这段代码使图像右对齐，并允许使用imageEdgeInsets和titleEdgeInsets进行宝贵的定位。

用你的自定义类子类化UIButton并添加:

- (CGRect)imageRectForContentRect:(CGRect)contentRect {
    CGRect frame = [super imageRectForContentRect:contentRect];
    CGFloat imageWidth = frame.size.width;
    CGRect titleRect = CGRectZero;
    titleRect.size = [[self titleForState:self.state] sizeWithAttributes:@{NSFontAttributeName: self.titleLabel.font}];
    titleRect.origin.x = (self.frame.size.width - (titleRect.size.width + imageWidth)) / 2.0 + self.titleEdgeInsets.left - self.titleEdgeInsets.right;
    frame.origin.x = titleRect.origin.x + titleRect.size.width - self.imageEdgeInsets.right + self.imageEdgeInsets.left;
    return frame;
}

- (CGRect)titleRectForContentRect:(CGRect)contentRect {
    CGFloat imageWidth = [self imageForState:self.state].size.width;
    CGRect frame = [super titleRectForContentRect:contentRect];
    frame.origin.x = (self.frame.size.width - (frame.size.width + imageWidth)) / 2.0 + self.titleEdgeInsets.left - self.titleEdgeInsets.right;
    return frame;
}

Xcode 11.4 Swift 5.2

对于任何试图镜像后退按钮样式的人，像这样的雪佛龙:

import UIKit

class NextBarButton: UIBarButtonItem {

    convenience init(target: Any, selector: Selector) {

        // Create UIButton
        let button = UIButton(frame: .zero)

        // Set Title
        button.setTitle("Next", for: .normal)
        button.setTitleColor(.systemBlue, for: .normal)
        button.titleLabel?.font = UIFont.systemFont(ofSize: 17)

        // Configure Symbol
        let config = UIImage.SymbolConfiguration(pointSize: 19.0, weight: .semibold, scale: .large)
        let image = UIImage(systemName: "chevron.right", withConfiguration: config)
        button.setImage(image, for: .normal)

        // Add Target
        button.addTarget(target, action: selector, for: .touchUpInside)

        // Put the Image on the right hand side of the button
        // Credit to liau-jian-jie for this part
        button.transform = CGAffineTransform(scaleX: -1.0, y: 1.0)
        button.titleLabel?.transform = CGAffineTransform(scaleX: -1.0, y: 1.0)
        button.imageView?.transform = CGAffineTransform(scaleX: -1.0, y: 1.0)

        // Customise spacing to match system Back button
        button.imageEdgeInsets = UIEdgeInsets(top: 0.0, left: -18.0, bottom: 0.0, right: 0.0)
        button.titleEdgeInsets = UIEdgeInsets(top: 0.0, left: -12.0, bottom: 0.0, right: 0.0)

        self.init(customView: button)
    }
}

实现:

override func viewDidLoad() {
    super.viewDidLoad()
    let nextButton = NextBarButton(target: self, selector: #selector(nextTapped))
    navigationItem.rightBarButtonItem = nextButton
}

@objc func nextTapped() {
    // your code
}

尽管一些建议的答案非常有创意和聪明，但最简单的解决方案如下:

button.semanticContentAttribute = UIApplication.shared
    .userInterfaceLayoutDirection == .rightToLeft ? .forceLeftToRight : .forceRightToLeft

就这么简单。作为奖励，在从右到左的区域中，图像将位于左侧。

编辑:这个问题已经被问过几次了，这是iOS 9 +。

要在UIButton内右对齐图像，请尝试下面的代码

btn.contentHorizontalAlignment = .right

约束条件呢?与semanticContentAttribute不同，它们不会改变语义。也许是这样的:

 button.rightAnchorconstraint(equalTo: button.rightAnchor).isActive = true

或者在Objective-C中:

[button.imageView.rightAnchor constraintEqualToAnchor:button.rightAnchor].isActive = YES;

警告:未经测试，iOS 9+