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Diff, Match and Patch Library, Objective C port

Diff, Match and Patch library for plain text

The Diff Match and Patch libraries offer robust algorithms to perform the operations required for synchronizing plain text.


  • Compare two blocks of plain text and efficiently return a list of differences.
  • Diff Demo


  • Given a search string, find its best fuzzy match in a block of plain text. Weighted for both accuracy and location.
  • Match Demo


  • Apply a list of patches onto plain text. Use best-effort to apply patch even when the underlying text doesn't match.
  • Patch Demo

Currently available in Java, JavaScript, Dart, C++, C#, Objective C, Lua and Python. Regardless of language, each library features the same API and the same functionality. All versions also have comprehensive test harnesses.


This library implements Myer's diff algorithm which is generally considered to be the best general-purpose diff. A layer of pre-diff speedups and post-diff cleanups surround the diff algorithm, improving both performance and output quality.

This library also implements a Bitap matching algorithm at the heart of a flexible matching and patching strategy.


Add “DiffMatchPatch.xcodeproj” to your project (preferably into “Frameworks” to keep things tidy).

In your target’s “Build Phases”:

  • Add Build Phase (+-button pull-down menu) > Copy Files
  • Destination: Frameworks
  • Change name to “Copy Frameworks” to keep things clean

Add “DiffMatchPatch.framework” to the following build phases (via the +-buttons):

  • “Target Dependencies”
  • “Link Binary With Libraries”
  • “Copy Frameworks” (created above)

And finally add the header to your code:

#import <DiffMatchPatch/DiffMatchPatch.h>


If you want to run the speed test, you first need to change the working directory of the executable “speedtest” to “Project directory”. This cannot be done beforehand, because this setting is stored in the current user’s project settings.