或者你可以只使用这个类别：

对象

@interface UIButton (VerticalLayout)

- (void)centerVerticallyWithPadding:(float)padding;
- (void)centerVertically;

@end

@implementation UIButton (VerticalLayout)

- (void)centerVerticallyWithPadding:(float)padding {
    CGSize imageSize = self.imageView.frame.size;
    CGSize titleSize = self.titleLabel.frame.size;
    CGFloat totalHeight = (imageSize.height + titleSize.height + padding);

    self.imageEdgeInsets = UIEdgeInsetsMake(- (totalHeight - imageSize.height),
                                            0.0f,
                                            0.0f,
                                            - titleSize.width);

    self.titleEdgeInsets = UIEdgeInsetsMake(0.0f,
                                            - imageSize.width,
                                            - (totalHeight - titleSize.height),
                                            0.0f);

    self.contentEdgeInsets = UIEdgeInsetsMake(0.0f,
                                              0.0f,
                                              titleSize.height,
                                              0.0f);
}

- (void)centerVertically {
    const CGFloat kDefaultPadding = 6.0f;
    [self centerVerticallyWithPadding:kDefaultPadding];
}

@end

快速扩展

extension UIButton {

    func centerVertically(padding: CGFloat = 6.0) {
        guard
            let imageViewSize = self.imageView?.frame.size,
            let titleLabelSize = self.titleLabel?.frame.size else {
            return
        }

        let totalHeight = imageViewSize.height + titleLabelSize.height + padding

        self.imageEdgeInsets = UIEdgeInsets(
            top: -(totalHeight - imageViewSize.height),
            left: 0.0,
            bottom: 0.0,
            right: -titleLabelSize.width
        )

        self.titleEdgeInsets = UIEdgeInsets(
            top: 0.0,
            left: -imageViewSize.width,
            bottom: -(totalHeight - titleLabelSize.height),
            right: 0.0
        )

        self.contentEdgeInsets = UIEdgeInsets(
            top: 0.0,
            left: 0.0,
            bottom: titleLabelSize.height,
            right: 0.0
        )
    }

}

建议： 如果按钮高度小于totalHeight，则图像将绘制外边框。

imageEdgeInset.top应该：

max(0, -(totalHeight - imageViewSize.height))