如何使用 @IBDesignable 属性为 UILabel 设置填充？答案

【问题标题】：How to set padding for UILabel using @IBDesignable property?如何使用 @IBDesignable 属性为 UILabel 设置填充？
【发布时间】：2016-08-22 12:21:02
【问题描述】：

这是UILabel 的子类的外观：

@IBDesignable class AttributedLabel: UILabel {

    @IBInspectable var padding: CGFloat = 0

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

我在情节提要中正确设置了padding，但它不起作用，因为填充仍然是0。

怎样做才能让它工作？是否可以在 Storyboard 中实时渲染？

【问题讨论】：

标签： ios swift uilabel ibdesignable

【解决方案1】：

这样使用；更改顶部、底部、左侧、右侧的内边距。

@IBDesignable class AttributedLabel: UILabel {

    @IBInspectable var topInset: CGFloat = 5.0
    @IBInspectable var bottomInset: CGFloat = 5.0
    @IBInspectable var leftInset: CGFloat = 7.0
    @IBInspectable var rightInset: CGFloat = 7.0

    override func drawTextInRect(rect: CGRect) {
        let insets = 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
    }
}

谢谢

【讨论】：

【解决方案2】：

您的子类看起来不完整。如文档中所述，您应该覆盖这两种方法：

public func textRectForBounds(bounds: CGRect, limitedToNumberOfLines numberOfLines: Int) -> CGRect
public func drawTextInRect(rect: CGRect)

这是一个应该可以工作的示例实现：

@IBDesignable class AttributedLabel : UILabel
{
    @IBInspectable var padding: CGFloat = 0 {
        didSet {
            self.textInsets = UIEdgeInsets(top: self.padding, left: self.padding, bottom: self.padding, right: self.padding)
        }
    }
    var textInsets = UIEdgeInsetsZero {
        didSet {
            self.invalidateIntrinsicContentSize()
        }
    }

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

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

您将无法在 Interface Builder 中实时呈现它。

【讨论】：

为什么不能在 Interface builder 中实时渲染？