简单的填充:

import UIKit

    class NewLabel: UILabel {

        override func textRectForBounds(bounds: CGRect, limitedToNumberOfLines numberOfLines: Int) -> CGRect {

            return CGRectInset(self.bounds, CGFloat(15.0), CGFloat(15.0))
        }

        override func drawRect(rect: CGRect) {

            super.drawTextInRect(CGRectInset(self.bounds,CGFloat(5.0), CGFloat(5.0)))
        }

    }

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))
    }
}

子类UILabel。(File-New-File- CocoaTouchClass-make UILabel的子类)。

//  sampleLabel.swift

import UIKit

class sampleLabel: UILabel {

 let topInset = CGFloat(5.0), bottomInset = CGFloat(5.0), leftInset = CGFloat(8.0), rightInset = CGFloat(8.0)

 override func drawTextInRect(rect: CGRect) {

  let insets: UIEdgeInsets = UIEdgeInsets(top: topInset, left: leftInset, bottom: bottomInset, right: rightInset)
  super.drawTextInRect(UIEdgeInsetsInsetRect(rect, insets))

 }
 override func intrinsicContentSize() -> CGSize {
  var intrinsicSuperViewContentSize = super.intrinsicContentSize()
  intrinsicSuperViewContentSize.height += topInset + bottomInset
  intrinsicSuperViewContentSize.width += leftInset + rightInset
  return intrinsicSuperViewContentSize
 }
}

ViewController:

override func viewDidLoad() {
  super.viewDidLoad()

  let labelName = sampleLabel(frame: CGRectMake(0, 100, 300, 25))
  labelName.text = "Sample Label"
  labelName.backgroundColor =  UIColor.grayColor()

  labelName.textColor = UIColor.redColor()
  labelName.shadowColor = UIColor.blackColor()
  labelName.font = UIFont(name: "HelveticaNeue", size: CGFloat(22))
  self.view.addSubview(labelName)
 }

或者将Storyboard上的自定义UILabel类关联为Label的类。

如果你想在textRect周围添加2px的填充，只需要这样做:

let insets = UIEdgeInsets(top: -2, left: -2, bottom: -2, right: -2)
label.frame = UIEdgeInsetsInsetRect(textRect, insets)

斯威夫特 4+

class EdgeInsetLabel: UILabel {
    var textInsets = 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: -textInsets.top,
                                          left: -textInsets.left,
                                          bottom: -textInsets.bottom,
                                          right: -textInsets.right)
        return textRect.inset(by: invertedInsets)
    }

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

用法:

let label = EdgeInsetLabel()
label.textInsets = UIEdgeInsets(top: 2, left: 6, bottom: 2, right: 6)

只需使用一个UIView作为一个superview，并定义一个固定的边距标签与自动布局。