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+

这里提到的解决方案停止工作，一旦我启用自动布局。我不得不提出我自己的想法:

子类UIButton和覆盖layoutSubviews方法:

//
//  MIThemeButtonImageAtRight.m
//  Created by Lukasz Margielewski on 7/9/13.
//

#import "MIThemeButtonImageAtRight.h"

static CGRect CGRectByApplyingUIEdgeInsets(CGRect frame, UIEdgeInsets insets);

@implementation MIThemeButtonImageAtRight

- (void)layoutSubviews
{
    [super layoutSubviews];

    CGRect contentFrame = CGRectByApplyingUIEdgeInsets(self.bounds, self.contentEdgeInsets);

    CGRect frameIcon = self.imageView.frame;
    CGRect frameText = self.titleLabel.frame;

    frameText.origin.x = CGRectGetMinX(contentFrame) + self.titleEdgeInsets.left;
    frameIcon.origin.x = CGRectGetMaxX(contentFrame) - CGRectGetWidth(frameIcon);

    self.imageView.frame = frameIcon;
    self.titleLabel.frame = frameText;
}

@end

static CGRect CGRectByApplyingUIEdgeInsets(CGRect frame, UIEdgeInsets insets){

    CGRect f = frame;

    f.origin.x += insets.left;
    f.size.width -= (insets.left + insets.right);
    f.origin.y += (insets.top);
    f.size.height -= (insets.top + insets.bottom);

    return f;

}

结果:

扩展UiButton并放入这些线条

    if let imageWidth = self.imageView?.frame.width {
        self.titleEdgeInsets = UIEdgeInsetsMake(0, -imageWidth, 0, imageWidth);
    }

    if let titleWidth = self.titleLabel?.frame.width {
        let spacing = titleWidth + 20
        self.imageEdgeInsets = UIEdgeInsetsMake(0, spacing, 0, -spacing);
    }

如果这需要在UIBarButtonItem中完成，则应该使用额外的视图包装 这是可行的

let view = UIView()
let button = UIButton()
button.setTitle("Skip", for: .normal)
button.setImage(#imageLiteral(resourceName:"forward_button"), for: .normal)
button.semanticContentAttribute = .forceRightToLeft
button.sizeToFit()
view.addSubview(button)
view.frame = button.bounds
navigationItem.rightBarButtonItem = UIBarButtonItem(customView: view)

这行不通

let button = UIButton()
button.setTitle("Skip", for: .normal)
button.setImage(#imageLiteral(resourceName:"forward_button"), for: .normal)
button.semanticContentAttribute = .forceRightToLeft
button.sizeToFit()
navigationItem.rightBarButtonItem = UIBarButtonItem(customView: button)

由于转换解决方案在iOS 11中不起作用，我决定编写一种新的方法。

调整按钮semanticContentAttribute可以让我们很好地将图像放到右边，而不必在文本更改时重新布局。因此它是理想溶液。然而，我仍然需要RTL的支持。事实上，一个应用程序不能改变它的布局方向在同一会话解决这个问题很容易。

话虽如此，它还是相当直截了当的。

extension UIButton {
    func alignImageRight() {
        if UIApplication.shared.userInterfaceLayoutDirection == .leftToRight {
            semanticContentAttribute = .forceRightToLeft
        }
        else {
            semanticContentAttribute = .forceLeftToRight
        }
    }
}

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)
        ])
    }
}