扩展的方法

使用扩展设置图像右侧自定义偏移

   extension UIButton {
    func addRightImage(image: UIImage, offset: CGFloat) {
        self.setImage(image, for: .normal)
        self.imageView?.translatesAutoresizingMaskIntoConstraints = false
        self.imageView?.centerYAnchor.constraint(equalTo: self.centerYAnchor, constant: 0.0).isActive = true
        self.imageView?.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: -offset).isActive = true
    }
}

在尝试了互联网上的多种解决方案后，我没有达到确切的要求。所以我最终编写了自定义实用程序代码。在将来帮助别人。 在swift 4.2上测试

// This function should be called in/after viewDidAppear to let view render
    func addArrowImageToButton(button: UIButton, arrowImage:UIImage = #imageLiteral(resourceName: "my_image_name") ) {
        let btnSize:CGFloat = 32
        let imageView = UIImageView(image: arrowImage)
        let btnFrame = button.frame
        imageView.frame = CGRect(x: btnFrame.width-btnSize-8, y: btnFrame.height/2 - btnSize/2, width: btnSize, height: btnSize)
        button.addSubview(imageView)
        //Imageview on Top of View
        button.bringSubviewToFront(imageView)
    }

我决定不使用标准的按钮图像视图，因为所提出的移动它的解决方案感觉很俗气。这让我获得了想要的美感，并且通过改变约束来重新定位按钮是很直观的:

extension UIButton {
    func addRightIcon(image: UIImage) {
        let imageView = UIImageView(image: image)
        imageView.translatesAutoresizingMaskIntoConstraints = false

        addSubview(imageView)

        let length = CGFloat(15)
        titleEdgeInsets.right += length

        NSLayoutConstraint.activate([
            imageView.leadingAnchor.constraint(equalTo: self.titleLabel!.trailingAnchor, constant: 10),
            imageView.centerYAnchor.constraint(equalTo: self.titleLabel!.centerYAnchor, constant: 0),
            imageView.widthAnchor.constraint(equalToConstant: length),
            imageView.heightAnchor.constraint(equalToConstant: length)
        ])
    }
}

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+

swift 3.0迁移 jasongregori给出的解

class ButtonIconRight: UIButton {
        override func imageRect(forContentRect contentRect: CGRect) -> CGRect {
            var imageFrame = super.imageRect(forContentRect: contentRect)
           imageFrame.origin.x = super.titleRect(forContentRect: contentRect).maxX - imageFrame.width
        return imageFrame
        }

        override func titleRect(forContentRect contentRect: CGRect) -> CGRect {
            var titleFrame = super.titleRect(forContentRect: contentRect)
            if (self.currentImage != nil) {
                titleFrame.origin.x = super.imageRect(forContentRect: contentRect).minX
            }
            return titleFrame
        }

最简单的解决方案:

iOS 10及以上版本，Swift:

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)

在iOS 10之前，Swift/Obj-C:

button.transform = CGAffineTransformMakeScale(-1.0, 1.0);
button.titleLabel.transform = CGAffineTransformMakeScale(-1.0, 1.0);
button.imageView.transform = CGAffineTransformMakeScale(-1.0, 1.0);

iOS 9及以上版本，Swift:(推荐)

button.semanticContentAttribute = .forceRightToLeft