要在UIButton内右对齐图像，请尝试下面的代码

btn.contentHorizontalAlignment = .right

当标题发生变化时，只需更新插图即可。你需要在另一侧用等量的、相反的插页来补偿插页。

[thebutton setTitle:title forState:UIControlStateNormal];
thebutton.titleEdgeInsets = UIEdgeInsetsMake(0, -thebutton.imageView.frame.size.width, 0, thebutton.imageView.frame.size.width);
thebutton.imageEdgeInsets = UIEdgeInsetsMake(0, thebutton.titleLabel.frame.size.width, 0, -thebutton.titleLabel.frame.size.width);

Swift 4 & 5

改变UIButton图像的方向(RTL和LTR)

extension UIButton {
    func changeDirection(){
       isArabic ? (self.contentHorizontalAlignment = .right) : (self.contentHorizontalAlignment = .left)
        // left-right margin 
        self.imageEdgeInsets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
        self.titleEdgeInsets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
    }
}

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)
          }
        }
     }

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
        }

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
    }
}