iOS - UILabel insets to zero is not worling

Question

我正在关注教程https://spin.atomicobject.com/2017/08/04/swift-extending-uilabel/因为我想删除 label 里面的填充。

该代码似乎非常有用，但我不让它工作：

import UIKit

@IBDesignable
class EdgeInsetLabel: UILabel {
    var textInsets = UIEdgeInsets.zero {
        didSet { invalidateIntrinsicContentSize() }
    }
    override func textRect(forBounds bounds: CGRect, 
        limitedToNumberOfLines numberOfLines: Int) -> CGRect {
        let insetRect = bounds.inset(by: textInsets)
        let textRect = super.textRect(forBounds: insetRect, 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))
    }
}

extension EdgeInsetLabel {
    @IBInspectable
    var leftTextInset: CGFloat {
        set { textInsets.left = newValue }
        get { return textInsets.left }
    }

    @IBInspectable
    var rightTextInset: CGFloat {
        set { textInsets.right = newValue }
        get { return textInsets.right }
    }

    @IBInspectable
    var topTextInset: CGFloat {
        set { textInsets.top = newValue }
        get { return textInsets.top }
    }

    @IBInspectable
    var bottomTextInset: CGFloat {
        set { textInsets.bottom = newValue }
        get { return textInsets.bottom }
    }
}

结果：

我错过了什么？

Answer 1

插图基于字体——而不是单个字符：

因此，使用UILabel中的默认系统字体，添加一些其他字符：

如果要将背景剪辑到单个字符的边界框，则需要使用Text Kit功能。 这是一个很好的起点： 使用 Text Kit 绘制和管理文本

Answer 2

使用myLabel.sizeToFit()删除 label 周围的任何可移动空间。

Answer 3

您缺少EdgeLabel子类中覆盖的textRect(forBounds:)部分：

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