这适用于多行标签:

class PaddedLabel: UILabel {
    var verticalPadding: CGFloat = 0
    var horizontalPadding: CGFloat = 0

    override func drawText(in rect: CGRect) {
        let insets = UIEdgeInsets(top: verticalPadding, left: horizontalPadding, bottom: verticalPadding, right: horizontalPadding)
        super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))
    }

    override var intrinsicContentSize: CGSize {
        get {
            let textWidth = super.intrinsicContentSize.width - horizontalPadding * 2
            let textHeight = sizeThatFits(CGSize(width: textWidth, height: .greatestFiniteMagnitude)).height
            let width = textWidth + horizontalPadding * 2
            let height = textHeight + verticalPadding * 2
            return CGSize(width: frame.width, height: height)
        }
    }
}

这适用于多行标签:

class PaddedLabel: UILabel {
    var verticalPadding: CGFloat = 0
    var horizontalPadding: CGFloat = 0

    override func drawText(in rect: CGRect) {
        let insets = UIEdgeInsets(top: verticalPadding, left: horizontalPadding, bottom: verticalPadding, right: horizontalPadding)
        super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))
    }

    override var intrinsicContentSize: CGSize {
        get {
            let textWidth = super.intrinsicContentSize.width - horizontalPadding * 2
            let textHeight = sizeThatFits(CGSize(width: textWidth, height: .greatestFiniteMagnitude)).height
            let width = textWidth + horizontalPadding * 2
            let height = textHeight + verticalPadding * 2
            return CGSize(width: frame.width, height: 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]];

也许你可以试试这段代码

CGRect frame = btn.titleLabel.frame;
int indent = 20;
int inset = 20;
[btn.titleLabel setFrame:CGRectMake(frame.origin.x+inset,frame.origin.y,frame.size.width+indent,frame.size.height)];

为UILabel添加填充的最佳方法是子类化UILabel并添加一个edgeInsets属性。然后设置所需的插图，标签将相应地绘制。

OSLabel.h

#import <UIKit/UIKit.h>

@interface OSLabel : UILabel

@property (nonatomic, assign) UIEdgeInsets edgeInsets;

@end

OSLabel.m

#import "OSLabel.h"

@implementation OSLabel

- (id)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        self.edgeInsets = UIEdgeInsetsMake(0, 0, 0, 0);
    }
    return self;
}

- (void)drawTextInRect:(CGRect)rect {
    [super drawTextInRect:UIEdgeInsetsInsetRect(rect, self.edgeInsets)];
}

- (CGSize)intrinsicContentSize
{
    CGSize size = [super intrinsicContentSize];
    size.width  += self.edgeInsets.left + self.edgeInsets.right;
    size.height += self.edgeInsets.top + self.edgeInsets.bottom;
    return size;
}

@end

blyabtroi的asnwer在Swift中转换(不需要子类化)

let style: NSMutableParagraphStyle = NSParagraphStyle.defaultParagraphStyle().mutableCopy() as! NSMutableParagraphStyle
style.alignment = .Justified
style.firstLineHeadIndent = 10.0
style.headIndent = 10.0
style.tailIndent = -10.0
let attrText: NSAttributedString = NSAttributedString(string: title, attributes: [NSParagraphStyleAttributeName:style])
let label: UILabel = UILabel(frame: someFrame)
label.numberOfLines = 0
label.attributedText = attrText