How to install ZXing in Xcode 4

After an upgrading to Xcode 4, I have been having trouble compiling my own ZXing iOS project.
So I decided to explain you how to install easily ZXing with Xcode 4.

First of all (for those who don’t know), ZXing is an open-source library to read the 1D/2D barcodes. This library is available on many platforms such as the iOS, Android, Blackberry, ect. You can find it here: http://code.google.com/p/zxing/.

Before to start, be sure that you have the latest version of ZXing on your computer. If you don’t, you must download it via a SVN client here: http://zxing.googlecode.com/svn/trunk/.

To use ZXing into your project in Xcode 4 follow these steps:

1. 
2. Firstly go to the “zxing/iphone/ZXingWidget/” and drag and drop the ZXingWidget.xcodeproj file onto your Xcode “Project navigator” sidebar. If a dialog appears uncheck the “Copy items” and verify that the “Reference Type” is “Relative to Project” before clicking “Add”.
   
3. Now we are going to add ZXingWidget as a dependency of your project to allow Xcode to compile it whenever you compile the main project:
   1. First select your project file in the “Project navigator”.
   2. Then select the corresponding target.
   3. After choose the “Build Phases” tab and expand the “Target Dependencies” section.
   4. Click the “+” (add) button to display a dialog.
   5. To finish add the “ZXingWidget” target as shown above.
   
4. Now we are going to link the ZXingWidget static library (libZXingWidget.a) to the project:
   1. Firstly choose the “Build Phases” tab and expand the “Link Binary With Libraries” section.
   2. Then click the “+” (add) button to display a dialog.
   3. To finish add the “libZXingWidget.a” which is located in the “Workspace” category as shown above.
   4. By the way add the following iOS frameworks too:
      • AddressBook
      • AddressBookUI
      • AudioToolbox
      • AVFoundation
      • CoreMedia
      • CoreVideo
      • libiconv.dylib
   
5. Then you must configure the header search path of your project to allow Xcode to find the ZXingWidget headers. To do that:
   1. In the “Project navigator” select the main project (not the target).
   2. Go to the “Build Settings” tab and search the “Header Search Paths“.
   3. Double-click on it and add:
      • The full path of the “zxing/iphone/ZXingWidget/Classes” directory. Check the “recursive path“.
      • The full path of the “zxing/cpp/core/src/” directory. Uncheck the “recursive path“.

Now you just have to import the “ZXingWidgetController.h” and the “QRCodeReader.h” to your project and use them.
Attention: Make sure that the files in which you are using the ZXing headers have the .mm extension because they use c++ library files.

Voilà! Now all should be ok. I hope it’ll help you!

转自：http://yannickloriot.com/2011/04/how-to-install-zxing-in-xcode-4/