NEW! Master Swift design patterns with my latest book! >>

How to render a PDF to an image

Paul Hudson       @twostraws

iOS has built-in APIs for drawing PDFs, which means it's relatively straight forward to render a PDF to an image. I say "relatively" because there's still some boilerplate you need to worry about: figuring out the document size, filling the background in a solid color to avoid transparency, and flipping the rendering so that the PDF draws the right way up.

To make things easy for you, here's a pre-made method you can use that takes a URL to a PDF and returns either a rendered image or nil if it failed. To call it you should pull out the URL to a resource in your bundle or another local PDF file.

func drawPDFfromURL(url: URL) -> UIImage? {
    guard let document = CGPDFDocument(url as CFURL) else { return nil }
    guard let page = document.page(at: 1) else { return nil }

    let pageRect = page.getBoxRect(.mediaBox)
    let renderer = UIGraphicsImageRenderer(size: pageRect.size)
    let img = renderer.image { ctx in
        UIColor.white.set()
        ctx.fill(pageRect)

        ctx.cgContext.translateBy(x: 0.0, y: pageRect.size.height)
        ctx.cgContext.scaleBy(x: 1.0, y: -1.0)

        ctx.cgContext.drawPDFPage(page)
    }

    return img
}

Available from iOS 3.0

Did this solution work for you? Please pass it on!

Other people are reading…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

Hacking with watchOS

Transfer your Swift skills to watchOS the easy way, and learn to build real-world apps in the process!

MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>