苹果PDFKit上的错误高亮注释答案

【问题标题】：Wrong highlight annotation on apple PDFKit苹果PDFKit上的错误高亮注释
【发布时间】：2017-11-24 08:51:56
【问题描述】：

我在 iOS 上使用 PDFKit 来突出显示文本（PDF 文件）。我通过创建 PDFAnnotation 并将其添加到选定的文本区域来做到这一点。我想精确地突出显示选定的区域，但它总是覆盖整条线，如下图所示。如何只为选定区域创建注释？？

我的代码：

        let highlight = PDFAnnotation(bounds: selectionText.bounds(for: page), forType: PDFAnnotationSubtype.highlight, withProperties: nil)
        highlight.color = highlightColor
        page.addAnnotation(highlight)

【问题讨论】：

标签： ios swift pdf pdfkit

【解决方案1】：

按照PDFKit Highlight Annotation: quadrilateralPoints 中的建议，您可以使用quadrilateralPoints 为同一注释添加不同的行高亮显示。

func highlight() {  
    guard let selection = pdfView.currentSelection, let currentPage = pdfView.currentPage else {return}
    let selectionBounds = selection.bounds(for: currentPage)
    let lineSelections = selection.selectionsByLine()

    let highlightAnnotation = PDFAnnotation(bounds: selectionBounds, forType: PDFAnnotationSubtype.highlight, withProperties: nil)

    highlightAnnotation.quadrilateralPoints = [NSValue]()
    for (index, lineSelection) in lineSelections.enumerated() {
        let n = index * 4
        let bounds = lineSelection.bounds(for: pdfView.currentPage!)
        let convertedBounds = bounds.convert(to: selectionBounds.origin)
        highlightAnnotation.quadrilateralPoints?.insert(NSValue(cgPoint: convertedBounds.topLeft), at: 0 + n)
        highlightAnnotation.quadrilateralPoints?.insert(NSValue(cgPoint: convertedBounds.topRight), at: 1 + n)
        highlightAnnotation.quadrilateralPoints?.insert(NSValue(cgPoint: convertedBounds.bottomLeft), at: 2 + n)
        highlightAnnotation.quadrilateralPoints?.insert(NSValue(cgPoint: convertedBounds.bottomRight), at: 3 + n)
    }

    pdfView.currentPage?.addAnnotation(highlightAnnotation)
}

extension CGRect {

    var topLeft: CGPoint {
        get {
            return CGPoint(x: self.origin.x, y: self.origin.y + self.height)
        }
    }

    var topRight: CGPoint {
        get {
            return CGPoint(x: self.origin.x + self.width, y: self.origin.y + self.height)
        }
    }

    var bottomLeft: CGPoint {
        get {
            return CGPoint(x: self.origin.x, y: self.origin.y)
        }
    }

    func convert(to origin: CGPoint) -> CGRect {
        return CGRect(x: self.origin.x - origin.x, y: self.origin.y - origin.y, width: self.width, height: self.height)
    }
}

【讨论】：

感谢quadrilateralPoints，我不知道。顺便说一句，扩展中缺少 bottomRight。

【解决方案2】：

PDFSelection bounds(forPage:) 方法返回一个矩形来满足整个选择区域。不是您的最佳解决方案。

尝试使用selectionsByLine()，并为每个矩形添加单独的注释，代表 PDF 中的每个选定行。示例：

    let selections = pdfView.currentSelection?.selectionsByLine()
    // Simple scenario, assuming your pdf is single-page.
    guard let page = selections?.first?.pages.first else { return }

    selections?.forEach({ selection in
        let highlight = PDFAnnotation(bounds: selection.bounds(for: page), forType: .highlight, withProperties: nil)
        highlight.endLineStyle = .square
        highlight.color = UIColor.orange.withAlphaComponent(0.5)

        page.addAnnotation(highlight)
    })

【讨论】：