The Extended Objective-C library extends the dynamism of the Objective-C programming language to support additional patterns present in other programming languages (including those that are not necessarily object-oriented).

libextobjc is meant to be very modular – most of its classes and modules can be used with no more than one or two dependencies.

# Features

libextobjc currently includes the following features:

 * **Safe categories**, using EXTSafeCategory, for adding methods to a class without overwriting anything already there (identifying conflicts for you).
 * **Concrete protocols**, using EXTConcreteProtocol, for providing default implementations of the methods in a protocol.
 * **Simpler and safer key paths**, using EXTKeyPathCoding, which automatically checks key paths at compile-time.
 * **Compile-time checking of selectors** to ensure that an object declares a given selector, using EXTSelectorChecking.
 * **Easier use of weak variables in blocks**, using `@weakify`, `@unsafeify`, and `@strongify` from the EXTScope module.
 * **Scope-based resource cleanup**, using `@onExit` in the EXTScope module, for automatically cleaning up manually-allocated memory, file handles, locks, etc., at the end of a scope.
 * **Algebraic data types** generated completely at compile-time, defined using EXTADT.
 * **Synthesized properties for categories**, using EXTSynthesize.
 * **Block-based coroutines**, using EXTCoroutine.
 * **EXTNil, which is like `NSNull`, but behaves much more closely to actual `nil`** (i.e., doesn't crash when sent unrecognized messages).
 * **Lots of extensions** and additional functionality built on top of `<objc/runtime.h>`, including extremely customizable method injection, reflection upon object properties, and various functions to extend class hierarchy checks and method lookups.

The [experimental](https://github.com/jspahrsummers/libextobjc/tree/experimental)
branch contains additional features that may be interesting, but are not
considered stable or safe for production use. Check out the headers for more
information.

# Running tests

To execute libextobjc's tests, first run `git submodule update --init --recursive`
to bring in the [xcconfigs](https://github.com/jspahrsummers/xcconfigs) submodule,
then open the project file and choose the desired test target.

# Adding to your project

If you want to add libextobjc as a dependency to an **application**, add the
repository as a [submodule](http://git-scm.com/book/en/Git-Tools-Submodules),
then include the source files you care about in your Xcode project.

If you want to add libextobjc as a dependency to a **framework or library**,
prefer [subtree merging](http://git-scm.com/book/en/Git-Tools-Subtree-Merging),
which will allow you to rename symbols to avoid conflicts, and make any tweaks
you need to for your library.

To create a libextobjc subtree:

```
$ git remote add libextobjc https://github.com/jspahrsummers/libextobjc.git
$ git fetch libextobjc
$ git read-tree --prefix=External/ -u libextobjc/master
$ git reset
```

Rename any symbols or change whatever you want, `git add` the specific files
that you want in your library, and then add them to your Xcode project.

To bring in upstream changes later:

```
$ git fetch -p libextobjc
$ git merge -Xsubtree=External/ libextobjc/master
$ git reset
```

Then, again, just add the changes you want.

# License

Released under the MIT License. See the
[LICENSE](https://github.com/jspahrsummers/libextobjc/blob/master/LICENSE.md)
file for more information.

# Requirements

libextobjc must be built with ARC enabled, and many of its macros require ARC in the calling files as well. MRR usage is not supported.