UIImage+PDF provides a UIImage class category method to render a UIImage from any PDF stored in the application bundle. The motivation for this was to enable the easy use of scaleable vector assets in iOS apps.

Usage

Add the sources files in the UIImage+PDF sub folder to your project. Use the following line to import the necessary methods.

#import "UIImage+PDF.h"

Then simply call one of the UIImage class methods as shown here:

UIImage *img = [ UIImage imageWithPDFNamed:@"YingYang.pdf" atSize:CGSizeMake( 40, 40 ) ];
UIImage *img = [ UIImage imageWithPDFNamed:@"YingYang.pdf" fitSize:CGSizeMake( 90, 50 ) ];
UIImage *img = [ UIImage imageWithPDFNamed:@"YingYang.pdf" atWidth:60 ];
UIImage *img = [ UIImage imageWithPDFNamed:@"YingYang.pdf" atHeight:90 ];
UIImage *img = [ UIImage originalSizeImageWithPDFNamed:@"YingYang.pdf" ];

UIImage *img = [ UIImage imageWithPDFURL:url atSize:CGSizeMake( 60, 60 ) atPage:1 ];

UIImage *img = [ UIImage imageWithPDFData:data atSize:CGSizeMake( 60, 60 ) atPage:1 ];

The fitSize:, atWidth: and atHeight: methods are particularly useful as they preserve the aspect ratio of the source PDF.

For a full API list consult the header file.

An example project is included in this repository. The important code is in viewDidLoad: in UIImage_PDF_exampleViewController.m.

ARC

If your project doesn't use ARC: you must add the -fobjc-arc compiler flag to NSData+MD5.m, NSString+MD5.m, PDFView.m, UIImage+PDF.m and UIView+Image.m in Target Settings ==> Build Phases ==> Compile Sources.

Disk Cacheing

UIImage+PDF now transparently caches all rendered PDFs in <Application_Home>/Library/Caches/__PDF_CACHE__. This substantially improves application latency with large PDFs, especially on the new iPad. To disable cacheing, comment out #define UIIMAGE_PDF_CACHEING 1 in UIImage+PDF.h.

Memory Cacheing

UIImage+PDF can now use NSCache to cache rendered PDFs in memory. This feature is disabled by default. To enable it call:

[ UIImage setShouldCacheInMemory:YES ];

PDF file size

By default Adobe Illustrator saves exported PDFs very inefficiently. For best results, select File -> Save a Copy, select PDF format and then uncheck all the general options. Once you are ready to ship your app, run all your PDF assets through ShrinkIt (see below).

Other vector graphics editors which natively use the OSX Quartz renderer, such as Sketch, will create much more compact PDFs.

The amazing devs at Panic have now released a PDF shrinking utility, ShrinkIt, which should take a lot of the pain out of a vector asset workflow.

Apps using UIImage+PDF

Here is a partial list of the apps using this category. If you want to add your app to this list, please submit a pull request.

• Vectoria
• Tiltoria
• Video Player+
• UltiScore

Licence

Copyright 2012 Nigel Timothy Barber - @mindbrix. All rights reserved.

Permission is given to use this source code file without charge in any project, commercial or otherwise, entirely at your risk, with the condition that any redistribution (in part or whole) of source code must retain this copyright and permission notice. Attribution in compiled projects is appreciated but not required.

Further Reading

Matt Gemmell has an excellent article on his blog explaining how to use PDF images in iOS apps.