简单的方法

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        self.view.addSubview(makeLabel("my title",x: 0, y: 100, w: 320, h: 30))
    }

    func makeLabel(title:String, x:CGFloat, y:CGFloat, w:CGFloat, h:CGFloat)->UILabel{
        var myLabel : UILabel = UILabel(frame: CGRectMake(x,y,w,h))
        myLabel.textAlignment = NSTextAlignment.Right

        // inser last char to right
        var titlePlus1char = "\(title)1"
        myLabel.text = titlePlus1char
        var titleSize:Int = count(titlePlus1char)-1

        myLabel.textColor = UIColor(red:1.0, green:1.0,blue:1.0,alpha:1.0)
        myLabel.backgroundColor = UIColor(red: 214/255, green: 167/255, blue: 0/255,alpha:1.0)


        // create myMutable String
        var myMutableString = NSMutableAttributedString()

        // create myMutable font
        myMutableString = NSMutableAttributedString(string: titlePlus1char, attributes: [NSFontAttributeName:UIFont(name: "HelveticaNeue", size: 20)!])

        // set margin size
        myMutableString.addAttribute(NSFontAttributeName, value: UIFont(name: "HelveticaNeue", size: 10)!, range: NSRange(location: titleSize,length: 1))

        // set last char to alpha 0
        myMutableString.addAttribute(NSForegroundColorAttributeName, value: UIColor(red:1.0, green:1.0,blue:1.0,alpha:0), range: NSRange(location: titleSize,length: 1))

        myLabel.attributedText = myMutableString

        return myLabel
    }


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}

没有故事板:

class PaddingLabel: UILabel {

    var topInset: CGFloat
    var bottomInset: CGFloat
    var leftInset: CGFloat
    var rightInset: CGFloat

    required init(withInsets top: CGFloat, _ bottom: CGFloat,_ left: CGFloat,_ right: CGFloat) {
        self.topInset = top
        self.bottomInset = bottom
        self.leftInset = left
        self.rightInset = right
        super.init(frame: CGRect.zero)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func drawText(in rect: CGRect) {
        let insets = UIEdgeInsets(top: topInset, left: leftInset, bottom: bottomInset, right: rightInset)
        super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))
    }

    override var intrinsicContentSize: CGSize {
        get {
            var contentSize = super.intrinsicContentSize
            contentSize.height += topInset + bottomInset
            contentSize.width += leftInset + rightInset
            return contentSize
        }
    }
}

用法:

let label = PaddingLabel(8, 8, 16, 16)
label.font = .boldSystemFont(ofSize: 16)
label.text = "Hello World"
label.backgroundColor = .black
label.textColor = .white
label.textAlignment = .center
label.layer.cornerRadius = 8
label.clipsToBounds = true
label.sizeToFit()

view.addSubview(label)

结果:

只需使用自动布局:

let paddedWidth = myLabel.intrinsicContentSize.width + 2 * padding
myLabel.widthAnchor.constraint(equalToConstant: paddedWidth).isActive = true

完成了。

如果你想使用UILabel

class UILabel : UIKit.UILabel {
    var insets = UIEdgeInsets.zero {
        didSet { invalidateIntrinsicContentSize() }
    }

    override func textRect(forBounds bounds: CGRect, limitedToNumberOfLines numberOfLines: Int) -> CGRect {
        let textRect = super.textRect(forBounds: bounds, limitedToNumberOfLines: numberOfLines)
        let invertedInsets = UIEdgeInsets(top: -insets.top,
                                          left: -insets.left,
                                          bottom: -insets.bottom,
                                          right: -insets.right)
        return textRect.inset(by: invertedInsets)
    }

    override func drawText(in rect: CGRect) {
        super.drawText(in: rect.inset(by: insets))
    }
}

就像其他答案一样，但它修复了一个bug:

当标签。宽度由自动布局控制，有时文本会被裁剪。

@IBDesignable
class InsetLabel: UILabel {

    @IBInspectable var topInset: CGFloat = 4.0
    @IBInspectable var leftInset: CGFloat = 4.0
    @IBInspectable var bottomInset: CGFloat = 4.0
    @IBInspectable var rightInset: CGFloat = 4.0

    var insets: UIEdgeInsets {
        get {
            return UIEdgeInsets.init(top: topInset, left: leftInset, bottom: bottomInset, right: rightInset)
        }
        set {
            topInset = newValue.top
            leftInset = newValue.left
            bottomInset = newValue.bottom
            rightInset = newValue.right
        }
    }

    override func sizeThatFits(_ size: CGSize) -> CGSize {
        var adjSize = super.sizeThatFits(size)
        adjSize.width += leftInset + rightInset
        adjSize.height += topInset + bottomInset
        return adjSize
    }

    override var intrinsicContentSize: CGSize {
        let systemContentSize = super.intrinsicContentSize
        let adjustSize = CGSize(width: systemContentSize.width + leftInset + rightInset, height: systemContentSize.height + topInset +     bottomInset)
        if adjustSize.width > preferredMaxLayoutWidth && preferredMaxLayoutWidth != 0 {
            let constraintSize = CGSize(width: bounds.width - (leftInset + rightInset), height: .greatestFiniteMagnitude)
            let newSize = super.sizeThatFits(constraintSize)
            return CGSize(width: systemContentSize.width, height: ceil(newSize.height) + topInset + bottomInset)
        } else {
            return adjustSize
        }
    }

    override func drawText(in rect: CGRect) {
        super.drawText(in: rect.inset(by: insets))
    }
}

类似于其他答案，但使用func类来动态地设置填充:

class UILabelExtendedView: UILabel
{
    var topInset: CGFloat = 4.0
    var bottomInset: CGFloat = 4.0
    var leftInset: CGFloat = 8.0
    var rightInset: CGFloat = 8.0

    override func drawText(in rect: CGRect)
    {
        let insets: UIEdgeInsets = UIEdgeInsets(top: topInset, left: leftInset, bottom: bottomInset, right: rightInset)
        super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))
    }

    override public var intrinsicContentSize: CGSize
    {
        var contentSize = super.intrinsicContentSize
        contentSize.height += topInset + bottomInset
        contentSize.width += leftInset + rightInset
        return contentSize
    }

    func setPadding(top: CGFloat, left: CGFloat, bottom: CGFloat, right: CGFloat){
        self.topInset = top
        self.bottomInset = bottom
        self.leftInset = left
        self.rightInset = right
        let insets: UIEdgeInsets = UIEdgeInsets(top: top, left: left, bottom: bottom, right: right)
        super.drawText(in: UIEdgeInsetsInsetRect(self.frame, insets))
    }
}