How to build multiple targets from a single Xcode Project

转自：http://www.omegasoftweb.com/omega/blog.cfm?p=43

How to build multiple targets (as in Lite Version and Full Version of an iPhone or iPad app) from a single Xcode Project

There are times you may find yourself needing to create multiple variations of an Xcode project, the most common example of which being a Lite Version and a Full Version of an iPhone app or iPad app. One option to accomplish this is to simply copy the project folder and rename it, working with each project separately from that point on. This is not a good idea, as now you have twice the work to manage things going forward, and confusions are bound to arise. My friendSmasher puts it succinctly: “in that path lies madness!”, and with this he is correct.

A much better plan is to configure your single Xcode project with multiple targets, so that you can develop multiple versions of the project concurrently and selectively build the one you need at a given moment. Here is a step by step guide to do just this, synthesized from the info in various threads at iphonedevsdk coupled with personal trial and error, and using the case of Lite Version / Full Version:

Step 1: Make a copy of your original target by right clicking the existing target and selecting “duplicate”. Rename this target to YourAppLite

Step 2: When you created the second target; a new pList file should have appeared in the resources folder YourApp-info_copy.pList or something similar; rename this to YourAppLite-info.pList

Step 3: Edit this new pList to have a different Bundle Identifier, com.yourcompany.YourAppLite, for example. If you do not do this both versions of your app will be seen as the same app instead of two unique ones, and when you build the light version it will overwrite your full version in the simulator or testing device.

Step 4: If you are going to use a different application icon for the light version (as you should), edit this new pList’s Icon file property to reference a different icon from the full version, IconLite.png for example. Obviously you must create this asset and add it to your project for this new icon to appear for the lite version.

Step 5: Highlight the new target (YourAppLite) and right click to “Get Info”, then navigate to the build tab and set Configuration to “All Configurations”. Now scroll down a bit until you find the “Info.plist file” parameter under the Packaging group; alter this to reference the new lite version pList we created above instead of the original pList.

Warning-Potential Gotcha:You may have noticed when you duplicated the target another product with the same name as the first appeared in the products folder. You may, like I was, be tempted to name the second one YourAppLite and change some properties in the pList to reflect this. Do NOT do this; there appears to be a bug which makes the debugger unable to launch the executable when you build. Furthermore, once you have done this even if you change the product name back it still gives the error. Perhaps this was just me being silly, but others have run into a similar issue; at any rate it is not necessary to change the product name for everything to work correctly, so I recommend leaving it alone.

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Now you should be all ready to built multiple targets, but there are still some things we want to do to make managing both branches as seamless as possible. Go grab a drink, then resume the adventure.
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Step 6: Once again highlight the new target (YourAppLite) and right click to “Get Info”, then navigate to the build tab and make sure Configuration is still on “All Configurations”. Now scroll down quite a ways until you find the “Other C Flags” parameter under the GCC Language group; alter this to be “-DLITE_VERSION” (the leading -D is necessary). What this does is allow you to do things like:

#ifdef LITE_VERSION
// Code unique to your lite version
#else
// Code unique to your full version
#endif

in your code, just like a normal if statement.

Step 7: For any project resources that only need to be in the lite version OR the full version, you can “Get Info” on the file and then navigate to the “Targets” tab, deselecting the unnecessary target. This will help to keep each respective bundle size down, and is especially useful for large packages like adMob (which you’d likely only want in your lite version). Keep in mind that removing assets from a target in this way will likely coincide with the type of branching code described in step 6.

Step 8 (Optional): If you want a separate Default.png file for your lite version, first create the file and name it DefaultLite.png and add it to your project along side the regular Default.png. Now, right click on your YourAppLite target, select Add –> New Build Phase –> New Run Script Build Phase and paste the following in the script field:

mv ${TARGET_BUILD_DIR}/${CONTENTS_FOLDER_PATH}/DefaultLite.png ${TARGET_BUILD_DIR}/${CONTENTS_FOLDER_PATH}/Default.png


Now close the window and expand the arrow next to YourAppLite target. You should see the run script you created, now grab it and move it just below “Copy Bundle Resources”. This will overwrite your Default.png with the DefaultLite.png at run time when you are building your lite version, just as you want.

Warning-Potential Weird Gotcha: Whenever I duplicate a target I notice that any Library Search Paths get slightly altered, so if you are using Library Search Paths and are getting strange errors, make sure you have the same values there in your Lite and Full version targets.

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And there you have it; multiple targets at your fingertips. Please feel free to leave some comments or point out any mistakes or gotchas. I hope you found this useful; good luck!
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