和@IBDesignable，使其与接口生成器一起工作

斯威夫特4

//
//  PaddedLabel.swift
//  TrainCentric
//
//  Created by Arsonik
//  https://stackoverflow.com/a/33244365/337934
//

import UIKit

@IBDesignable
class PaddedLabel: UILabel {

    @IBInspectable var inset:CGSize = CGSize(width: 0, height: 0)

    var padding: UIEdgeInsets {
        var hasText:Bool = false
        if let t = self.text?.count, t > 0 {
            hasText = true
        }
        else if let t = attributedText?.length, t > 0 {
            hasText = true
        }

        return hasText ? UIEdgeInsets(top: inset.height, left: inset.width, bottom: inset.height, right: inset.width) : UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
    }

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

    override var intrinsicContentSize: CGSize {
        let superContentSize = super.intrinsicContentSize
        let p = padding
        let width = superContentSize.width + p.left + p.right
        let heigth = superContentSize.height + p.top + p.bottom
        return CGSize(width: width, height: heigth)
    }

    override func sizeThatFits(_ size: CGSize) -> CGSize {
        let superSizeThatFits = super.sizeThatFits(size)
        let p = padding
        let width = superSizeThatFits.width + p.left + p.right
        let heigth = superSizeThatFits.height + p.top + p.bottom
        return CGSize(width: width, height: heigth)
    }
}

斯威夫特2

@IBDesignable
class PaddedLabel: UILabel {

    @IBInspectable var inset:CGSize = CGSize(width: 0, height: 0)

    var padding: UIEdgeInsets {
        var hasText:Bool = false
        if let t = text?.length where t > 0 {
            hasText = true
        }
        else if let t = attributedText?.length where t > 0 {
            hasText = true
        }

        return hasText ? UIEdgeInsets(top: inset.height, left: inset.width, bottom: inset.height, right: inset.width) : UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
    }

    override func drawTextInRect(rect: CGRect) {
        super.drawTextInRect(UIEdgeInsetsInsetRect(rect, padding))
    }

    override func intrinsicContentSize() -> CGSize {
        let superContentSize = super.intrinsicContentSize()
        let p = padding
        let width = superContentSize.width + p.left + p.right
        let heigth = superContentSize.height + p.top + p.bottom
        return CGSize(width: width, height: heigth)
    }

    override func sizeThatFits(size: CGSize) -> CGSize {
        let superSizeThatFits = super.sizeThatFits(size)
        let p = padding
        let width = superSizeThatFits.width + p.left + p.right
        let heigth = superSizeThatFits.height + p.top + p.bottom
        return CGSize(width: width, height: heigth)
    }
}

如果你在ios6 +中使用自动布局，你可以通过在UILabel的子类中调整intrinsicContentSize来实现。

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.textAlignment = NSTextAlignmentRight;
    }
    return self;
}

- (CGSize)intrinsicContentSize 
{
    CGSize size = [super intrinsicContentSize];
    return CGSizeMake(size.width + 10.0, size.height);
}

如果是单行，只需在左侧添加空格，超过一行的填充将再次为0。

[self.myLabel setText:[NSString stringWithFormat:@"   %@", self.myShortString]];

设置标签的textAlignment属性为NSTextAlignmentRight并增加它的宽度。

对于这样一个简单的情况，子类化有点麻烦。另一种方法是将没有背景设置的UILabel添加到有背景设置的UIView中。将标签的x设置为10，并使外部视图的大小比标签宽20个像素。

你也可以用一个自定义框架初始化你的UILabel来解决这个问题。

    CGRect initialFrame = CGRectMake(0, 0, 100, 100);
    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0, 10, 0, 0);
    CGRect paddedFrame = UIEdgeInsetsInsetRect(initialFrame, contentInsets);

    self.label = [[UILabel alloc] initWithFrame:paddedFrame];

向CGRect Tricks致敬。