对于Xamarin用户(使用统一API):

class UIMarginLabel : UILabel
{
    public UIMarginLabel()
    {
    }

    public UIMarginLabel( CGRect frame ) : base( frame )
    {
    }

    public UIEdgeInsets Insets { get; set; }

    public override void DrawText( CGRect rect )
    {
        base.DrawText( Insets.InsetRect( rect ) );
    }
}

对于那些使用原始MonoTouch API的人:

public class UIMarginLabel : UILabel
{
    public UIEdgeInsets Insets { get; set; }

    public UIMarginLabel() : base()
    {
        Insets = new UIEdgeInsets(0, 0, 0, 0);
    }
    public UIMarginLabel(RectangleF frame) : base(frame)
    {
        Insets = new UIEdgeInsets(0, 0, 0, 0);
    }

    public override void DrawText(RectangleF frame)
    {
        base.DrawText(new RectangleF(
            frame.X + Insets.Left,
            frame.Y + Insets.Top,
            frame.Width - Insets.Left - Insets.Right,
            frame.Height - Insets.Top - Insets.Bottom));
    }
}

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)];

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。

我通过子类化UILabel和重写drawTextInRect来解决这个问题:

- (void)drawTextInRect:(CGRect)rect {
    UIEdgeInsets insets = {0, 5, 0, 5};
    [super drawTextInRect:UIEdgeInsetsInsetRect(rect, insets)];
}

斯威夫特3.1:

override func drawText(in rect: CGRect) {
    let insets = UIEdgeInsets.init(top: 0, left: 5, bottom: 0, right: 5)
    super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))
}

斯威夫特4.2.1:准备

override func drawText(in rect: CGRect) {
    let insets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
    super.drawText(in: rect.inset(by: insets))
}

你可能已经猜到了，这是对tc的改编。的答案。它有两个优点:

没有必要通过发送sizeToFit消息来触发它 它只保留标签框架——如果你的标签有背景，而你不想让它缩小，这很方便

这是我发现的最简单的方法。这对我来说很有魔力。

UIView *titleSection = [[UIView alloc] initWithFrame:CGRectMake(0, 0, screenWidth, 100)];
[titleSection addSubview:titleSection];

UILabel *label = [[UILabel alloc] initWithFrame:CGRectInset(titleSection.frame, PADDING, 0)];
[titleSection addSubview:label];

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