在Swift 3中有一种优雅的方式，更好地理解:

override func imageRect(forContentRect contentRect: CGRect) -> CGRect {
    let leftMargin:CGFloat = 40
    let imgWidth:CGFloat = 24
    let imgHeight:CGFloat = 24
    return CGRect(x: leftMargin, y: (contentRect.size.height-imgHeight) * 0.5, width: imgWidth, height: imgHeight)
}

override func titleRect(forContentRect contentRect: CGRect) -> CGRect {
    let leftMargin:CGFloat = 80
    let rightMargin:CGFloat = 80
    return CGRect(x: leftMargin, y: 0, width: contentRect.size.width-leftMargin-rightMargin, height: contentRect.size.height)
}
override func backgroundRect(forBounds bounds: CGRect) -> CGRect {
    let leftMargin:CGFloat = 10
    let rightMargin:CGFloat = 10
    let topMargin:CGFloat = 10
    let bottomMargin:CGFloat = 10
    return CGRect(x: leftMargin, y: topMargin, width: bounds.size.width-leftMargin-rightMargin, height: bounds.size.height-topMargin-bottomMargin)
}
override func contentRect(forBounds bounds: CGRect) -> CGRect {
    let leftMargin:CGFloat = 5
    let rightMargin:CGFloat = 5
    let topMargin:CGFloat = 5
    let bottomMargin:CGFloat = 5
    return CGRect(x: leftMargin, y: topMargin, width: bounds.size.width-leftMargin-rightMargin, height: bounds.size.height-topMargin-bottomMargin)
}

我来这个派对有点晚，但我想我有一些有用的东西要补充。

Kekoa的答案很好，但正如RonLugge所提到的，它会使按钮不再尊重sizeToFit，更重要的是，它会导致按钮在固有大小时剪辑其内容。呵!

不过,首先

简单解释一下我是如何相信imageEdgeInsets和titleEdgeInsets工作的:

imageEdgeInsets的文档有以下内容:

使用此属性可调整按钮图像的有效绘图矩形的大小和位置。您可以为这四个嵌入(顶部、左侧、底部、右侧)中的每一个指定不同的值。正值会缩小或插入这条边——使它更靠近按钮的中心。负值会使这条边扩大或开始。

我相信这个文档是在想象这个按钮没有标题，只有一个图像的情况下编写的。用这种方式思考更有意义，并且表现得像UIEdgeInsets通常做的那样。基本上，图像的帧(或标题，带有titleEdgeInsets)对于正插入向内移动，对于负插入向外移动。

好吧，那又怎样?

我快到了!这是你默认设置的，设置一个图像和一个标题(按钮边框是绿色的，只是为了显示它的位置):

当你想要图像和标题之间有空格，而又不造成两者被压缩时，你需要设置四个不同的insets，图像和标题各两个。这是因为你不想改变这些元素帧的大小，而只是改变它们的位置。当你开始以这种方式思考时，Kekoa的优秀类别所需要的改变就变得清晰起来:

@implementation UIButton(ImageTitleCentering)

- (void)centerButtonAndImageWithSpacing:(CGFloat)spacing {
    CGFloat insetAmount = spacing / 2.0;
    self.imageEdgeInsets = UIEdgeInsetsMake(0, -insetAmount, 0, insetAmount);
    self.titleEdgeInsets = UIEdgeInsetsMake(0, insetAmount, 0, -insetAmount);
}

@end

但是等等，你说，当我这样做的时候，我得到了这个:

噢,是的!我忘了，医生警告过我。他们部分地说:

此属性仅用于布局期间定位图像。按钮不使用此属性来确定intrinsicContentSize和sizeThatFits:。

但有一个属性可以提供帮助，那就是contenttedgeinsets。这方面的医生说:

按钮使用这个属性来确定intrinsicContentSize和sizeThatFits:。

听起来不错。所以让我们再一次调整这个类别:

@implementation UIButton(ImageTitleCentering)

- (void)centerButtonAndImageWithSpacing:(CGFloat)spacing {
    CGFloat insetAmount = spacing / 2.0;
    self.imageEdgeInsets = UIEdgeInsetsMake(0, -insetAmount, 0, insetAmount);
    self.titleEdgeInsets = UIEdgeInsetsMake(0, insetAmount, 0, -insetAmount);
    self.contentEdgeInsets = UIEdgeInsetsMake(0, insetAmount, 0, insetAmount);
}

@end

得到什么?

在我看来是赢家。

在Swift中工作，却不想做任何思考?下面是Swift扩展的最终版本:

extension UIButton {

    func centerTextAndImage(spacing: CGFloat) {
        let insetAmount = spacing / 2
        let isRTL = UIView.userInterfaceLayoutDirection(for: semanticContentAttribute) == .rightToLeft
        if isRTL {
           imageEdgeInsets = UIEdgeInsets(top: 0, left: insetAmount, bottom: 0, right: -insetAmount)
           titleEdgeInsets = UIEdgeInsets(top: 0, left: -insetAmount, bottom: 0, right: insetAmount)
           contentEdgeInsets = UIEdgeInsets(top: 0, left: -insetAmount, bottom: 0, right: -insetAmount)
        } else {
           imageEdgeInsets = UIEdgeInsets(top: 0, left: -insetAmount, bottom: 0, right: insetAmount)
           titleEdgeInsets = UIEdgeInsets(top: 0, left: insetAmount, bottom: 0, right: -insetAmount)
           contentEdgeInsets = UIEdgeInsets(top: 0, left: insetAmount, bottom: 0, right: insetAmount)
        }
    }
}

你可以用这个——来避免很多麻烦

myButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;   
myButton.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;

这将自动对齐你所有的内容到左边(或任何你想要的地方)

斯威夫特3:

myButton.contentHorizontalAlignment = UIControlContentHorizontalAlignment.left;   
myButton.contentVerticalAlignment = UIControlContentVerticalAlignment.center;

在Swift 3中有一种优雅的方式，更好地理解:

override func imageRect(forContentRect contentRect: CGRect) -> CGRect {
    let leftMargin:CGFloat = 40
    let imgWidth:CGFloat = 24
    let imgHeight:CGFloat = 24
    return CGRect(x: leftMargin, y: (contentRect.size.height-imgHeight) * 0.5, width: imgWidth, height: imgHeight)
}

override func titleRect(forContentRect contentRect: CGRect) -> CGRect {
    let leftMargin:CGFloat = 80
    let rightMargin:CGFloat = 80
    return CGRect(x: leftMargin, y: 0, width: contentRect.size.width-leftMargin-rightMargin, height: contentRect.size.height)
}
override func backgroundRect(forBounds bounds: CGRect) -> CGRect {
    let leftMargin:CGFloat = 10
    let rightMargin:CGFloat = 10
    let topMargin:CGFloat = 10
    let bottomMargin:CGFloat = 10
    return CGRect(x: leftMargin, y: topMargin, width: bounds.size.width-leftMargin-rightMargin, height: bounds.size.height-topMargin-bottomMargin)
}
override func contentRect(forBounds bounds: CGRect) -> CGRect {
    let leftMargin:CGFloat = 5
    let rightMargin:CGFloat = 5
    let topMargin:CGFloat = 5
    let bottomMargin:CGFloat = 5
    return CGRect(x: leftMargin, y: topMargin, width: bounds.size.width-leftMargin-rightMargin, height: bounds.size.height-topMargin-bottomMargin)
}

快4.倍

extension UIButton {
    func centerTextAndImage(spacing: CGFloat) {
        let insetAmount = spacing / 2
        let writingDirection = UIApplication.shared.userInterfaceLayoutDirection
        let factor: CGFloat = writingDirection == .leftToRight ? 1 : -1

        self.imageEdgeInsets = UIEdgeInsets(top: 0, left: -insetAmount*factor, bottom: 0, right: insetAmount*factor)
        self.titleEdgeInsets = UIEdgeInsets(top: 0, left: insetAmount*factor, bottom: 0, right: -insetAmount*factor)
        self.contentEdgeInsets = UIEdgeInsets(top: 0, left: insetAmount, bottom: 0, right: insetAmount)
    }
}

用法:

button.centerTextAndImage(spacing: 10.0)

在Xcode 8.0中，你可以通过改变大小检查器中的insets来实现。

选择UIButton ->属性检查器->进入大小检查器，修改内容，图像和标题插入。

如果你想改变右边的图像，你可以简单地在属性检查器中将语义属性更改为强制从右向左。