iOSでPDFを表示してみる

iOSでPDFを表示する方法を知らなかったのでメモ書き

//: Playground - noun: a place where people can play

import PlaygroundSupport
import UIKit
import CoreGraphics

class PDFView: UIView {
    var page: CGPDFPage?

    override func draw(_ rect: CGRect) {
        guard let page = page else { return }

        guard let context = UIGraphicsGetCurrentContext() else {
            fatalError()
        }

        context.translateBy(x: 0, y: rect.size.height)
        context.scaleBy(x: 1.0, y: -1.0)

        let box = page.getBoxRect(.mediaBox)

        let xScale = rect.size.width / box.size.width
        let yScale = rect.size.height / box.size.height
        let scale = min(xScale, yScale)

        let tx = (rect.size.width - box.size.width * scale) / 2
        let ty = (rect.size.height - box.size.height * scale) / 2

        context.translateBy(x: tx, y: ty)
        context.scaleBy(x: scale, y: scale)
        context.drawPDFPage(page)
    }
}

guard let url = NSURL(string: "http://devstreaming.apple.com/videos/wwdc/2016/402h429l9d0hy98c9m6/402/402_whats_new_in_swift.pdf"), let doc = CGPDFDocument(url) else {
    fatalError()
}

let pageCount = doc.numberOfPages
let number = 1
let page = doc.page(at: number)

let view = PDFView(frame: UIScreen.main.bounds)
view.backgroundColor = UIColor.lightGray
view.page = page

PlaygroundPage.current.liveView = view

上のコードはPlaygroundで検証しました。PlaygroundPage.current.liveView = viewでPlaygroundでもViewの検証ができます。

今回はシングルページの表示ですが、doc.page(at: number)でページを切り替えれるので、簡単にPDFViewerみたいなアプリも作れそうですね