error: Multiple commands produce '/Users/uesr/Library/Developer/Xcode/DerivedData/OptimalLive-fxatvygbofczeyhjsawtebkimvwx/Build/Products/Debug-iphoneos/OptimalLive.app/Info.plist':
1) Target 'OptimalLive' has copy command from '/Users/uesr/Desktop/workSpace/SEALIVE/SeaLive1.1/OptimalLive/Info.plist' to '/Users/uesr/Library/Developer/Xcode/DerivedData/OptimalLive-fxatvygbofczeyhjsawtebkimvwx/Build/Products/Debug-iphoneos/OptimalLive.app/Info.plist'
2) Target 'OptimalLive' has copy command from '/Users/uesr/Desktop/workSpace/SEALIVE/SeaLive1.1/OptimalLive/Server/Masonry/Info.plist' to '/Users/uesr/Library/Developer/Xcode/DerivedData/OptimalLive-fxatvygbofczeyhjsawtebkimvwx/Build/Products/Debug-iphoneos/OptimalLive.app/Info.plist'
3) Target 'OptimalLive' has process command with input '/Users/uesr/Desktop/workSpace/SEALIVE/SeaLive1.1/OptimalLive/Info.plist'
Running the code in Xcode 9 works, but there is an error in Xcode 10.
The issue might be occurring because of multiple Plist or other files within App-
Solution -> Open target -> Build phases > Copy Bundle Resources and remove info.plist from there.
Note: If you have developed a watch app too then you will have to remove the plist from the watch and watch-extension too.
This answer is deprecated - Xcode 12 has deprecated the Legacy Build System, it will be removed in a further release
I found the solution for this build error, for anybody else having the same issue with Xcode 10 build system, follow the following steps to fix it:
In Xcode, go to File->Project/Workspace settings.
Change the build system to Legacy Build system.
It will resolve the build issue with the new Xcode 10.
If you want to work with the new build system, then you can find the troubleshooting help from this apple Xcode help page.
Go to Xcode -> File ->Workspace Settings.
You will find one pop up like.
Select "Legacy Build System" from Build System tag.
Press on "Done"
Note:- Make sure clear your project with "cmd+shift+alt+k" and "Derived Data"
Build your project it will work charm :)
I was experimenting with Core Data. I built a data model for a simple checklist program and generated the NSManagedObjects. When I compiled the project I got the following error:
error: Multiple commands produce '/Users/myUSerName/Library/Developer/Xcode/DerivedData/myCoreDateExperiment-gzbslaqdwglkzxemijpdqmizgyzc/Build/Intermediates.noindex/ myCoreDateExperiment /Debug-iphonesimulator/ myCoreDateExperiment.build/Objects-normal/x86_64/CheckListItem+CoreDataProperties.o':
1) Target ' myCoreDateExperiment ' (project ' myCoreDateExperiment ') has compile command for Swift source files
2) Target ' myCoreDateExperiment ' (project ' myCoreDateExperiment ') has compile command for Swift source files
The problem was the data model (CheckList.xcdatamodeld in my case) was in the "Compile Sources" list. The project compiled cleanly when I removed it from the list.
Open the project navigator and select the project (very first entry at the top)
Select your build target under Targets in the "Projects and Targets" pane
Select Build Phases option near the top
Expand the "Compile Sources" entry and look for your data model name. Search for "xcdatamodeld" if you have trouble finding it.
Delete the model from the compile list
Make sure the data model is included in the "Copy Bundle Resources" list. Add it if it is missing.
EDIT
As #WilliamT. explains in the comments, you need the xcdatamodeld in the compile list. Instead, go to your entities within the xcdatamodeld file. Select the models that are erroring, expand the left panel, and change the field of "Codegen" to "Manual/None".
This answer is deprecated - XCode 12 has deprecated the Legacy Build System, it will be removed in a further release
Try this as well.
Xcode->File->Project Settings-> Build System -> Legacy Build System.
If you are getting this from the Ditto command creating multiple instances of the same name (NOT the 'copy files' build phase), you may have to change the Product Module Name.
Click on your Target(s) Xcode is complaining about
Click on Build Settings
Search for Product Module Name
Change the name to something unique
We have a watch target and a few notification targets in our app, so I just put things like Extension on the end of the module name.
I found this solution originally here: https://forums.developer.apple.com/thread/103913
If you use CocoaPods you may want to try deintegrate the pods and install again. It works for me.
pod deintegrate
pod install
While checking the build log, I noticed a warning:
note: Using new build system
note: Planning build
note: Constructing build description
Build system information
warning: The Copy Bundle Resources build phase contains this target's Info.plist file '/Users/<redacted>/Repositories/Whitesmith/optimize-ios/Carthage/Checkouts/WSStatusBarNotification/Miscellaneous/Info.plist'. (in target 'JDStatusBarNotification')
So, if that's your case then just go to your target:
Build Phases
Copy Bundle Resource
Remove info.plist.
Read this answer if error message references Core Data files
Synopsis: You may have both automatically-generated and manually-generated Core Data managed object class files.
This answer applies if the first line of the error refers to a Foo+CoreDataProperties.o or Foo+CoreDataClass.o file. Example:
error: Multiple commands produce '/Users/me/Library/Developer/Xcode/DerivedData/MyApp-uebslaqdwgldkjemijpdqmizgyzc/Build/Intermediates.noindex/ MyApp /Debug-iphonesimulator/ MyApp.build/Objects-normal/x86_64/Foo+CoreDataProperties.o':
1) Target ' MyApp ' (project ' MyApp ') has compile command for Swift source files
2) Target ' MyApp ' (project ' MyApp ') has compile command for Swift source files
The root cause can be seen by expanding the Compile Swift Source Files section of the Build Transcript. For example:
<unknown>:0: error: filename "Address+CoreDataClass.swift" used twice: '/Users/myUserName/Projects/Jnky/Foo+CoreDataProperties' and '/Users/jk/myUserName/Developer/Xcode/DerivedData/MyApp-uebslaqdwgldkjemijpdqmizgyzc/Build/Intermediates.noindex/MyApp.build/Debug/MyApp.build/DerivedSources/CoreDataGenerated/Jnky/Foo+CoreDataProperties.swift'
The first file mentioned there is a source file in your project directory, which someone generated by selecting your data model in the Project Navigator and clicking in the menu Editor > Create Managed Object Subclass. This feature was added in Xcode 7 or so.
The second file is a file of the same name but which is buried in Xcode's DerivedData. This file is generated automatically by Xcode during every build if the data model (.xcdatamodeld) file is included in the target's Compile Sources build phase. This feature was added in Xcode 9 or so. Zero, one or two files are generated for each entity/class, depending on the setting of the Codegen popup. That popup is in the Data Model Inspector when you select an entity while editing your data model…
The settings are:
Manual/None No files are generated
Category/Extension One file, Foo+CoreDataProperties.m or .swift is generated, containing an Objective-C category or Swift extension.
Class Definition That same Category/Extension file is generated, and in addition a Foo+CoreDataClass.m or .swift is generated, containing class declaration and definition.
So you see the problem occurs when a developer (like me) who is accustomed to the older Xcode begins a project in a newer Xcode. We think that we need to use the Create Managed Object Subclass menu item, which we do, to create the files we can see in the Project Navigator while not realizing that our settings in the Codegen popup are causing Xcode to create duplicate files, which Apple "cleverly" does not show in the Project Navigator, because they don't trust developers to read and heed the comment in the header // This file was automatically generated and should not be edited.
Solution 1 - Use the Older Way
You can disable all automatic Codegen for a data model with just one setting:
Open the problem Target's Build Phases (In Project Navigator, select project, then in list of TARGETS which appears, select the problem target, then tab Build Phases).
Expand the Compile Sources entry and find the problem data model (.xcdatamodeld file).
Delete it from the compile list
Ensure the data model is included in the Copy Bundle Resources list.
Solution 2 - Core Data Magic For Beginners
Here, you go all in on the newer way.
Leave your data model as is in that Compile Sources.
In each Entity Inspector in your data model, set Codegen to Class Definition.
In the Project Navigator, delete and trash any Foo+CoreDataClass files, and rename any Foo+CoreDataProperties.m or .swift files to something like Foo+MyProperties.
In each Foo+MyProperties.m or .swift file, if there are properties generated by Xcode, delete these properties because they will be in the hidden files created by Codegen.
With this solution, your class definitions are generated automatically from the data model on each build. You can't even see them. It is Core Data Magic, nice and simple for beginners.
Solution 3 - For Most Real-World Apps
But Solution 2 is no good if you really want to add non-managed properties. (Objective-C does not allow properties to be added in categories, and Swift does not allow stored properties to be added in extensions.) So in most real-world apps, you probably want to go halfway between Solutions 1 and 2…
Leave your data model in the list of Compile Sources
In each Entity Inspector in your data model, set Codegen to Category/Extension.
In the Project Navigator, delete and trash any Foo+CoreDataClass.m or .swift files, and, to reduce future confusion, rename any Foo+CoreDataProperties.m or .swift files to maybe just Foo.m or .swift.
Ensure that each Foo.m or .swift file contains the class definition, to which you can add your own non-managed properties.
(Acknowledgments to the answer by Positron. My answer here explains why Positron's answer (my Solution 1) works, and adds Solution 2 and Solution 3.)
Solution 1 :
Open target ➼ Build phases ➼ Copy Bundle Resources ➼ remove info.plist from there. ➼ you will have to remove the plist from the Extensions too (if any).
Solution 2:
If you use CocoaPods you may want to try deintegrate the pods and install again.
Commands:
1) pod deintegrate
2) pod install
Solution 3:
In Xcode, go to File ➼ Project/Workspace settings.
➼ Change the build system to Legacy Build system.
I had the same problem, I had a one more helper app in main App and copy this in resource. In my case solved as :-
1) Target -> 2)Build Phases 2) Copy File (n items) 3) Remove Copy File.
The Helper app automatically copied in Xcode 10.0.
Try this Its Working :
In Xcode, go to File->Project/Workspace settings.
Change the build system to Legacy Build system.
None of the solutions proposed here worked for me. This was particularly due to CocoaPods. I was previously using Cocoapods 1.3.1. Simply upgrading to 1.5.3 didn't resolve the issue right away.
The steps I followed were:
Delete Podfile.lock
Delete Pods directory
Delete Derived Data & Clean
Exit Xcode
Update CocoaPods to 1.5.3
Run pod install
Open workspace and build
One option which solved my issue is to changing build system to legacy build system. Please follow the following steps in Xcode 10+.
Here I have written a detailed article on the problem & its solution. Xcode Error: Multiple commands produce
In my case PDFGenerator was producing an info.plist file, I just deleted it.
This answer is deprecated - Xcode 12 has deprecated the Legacy Build System, it will be removed in a further release
I'm using Xcode 11.4
Can't build old project
Xcode => File => Project Settings => Build System => Legacy Build System
Before I begin note that my project utilizes Carthage as a dependency manager.
None of the existing answers here resolved my issue. What did resolve the issue for me was the following.
First, I noticed that the build error pointed out one framework in particular. Next I filtered App Target > Build Phases for that framework. I noticed that that framework was present in both "Link Binary With Libraries" and "Embed Frameworks". Noting that none of the frameworks listed under "Embed Frameworks" were ones managed by Carthage I removed the framework in question from "Embed Frameworks". I then re-built my project and everything works fine including the functionality enabled by the framework in question.
This issue arose for me after adding a second part of the Fabric suite of SDKs to the app.
What actually happened was that the GoogleUtilies Framework was added twice to the Pods project
This would have been fine prior to Xcode 10 but Xcode 10 will complain if a file has two actions against it (in this case a copy action).
It's safe to remove the second framework.
there are some reasons that cause this error to be shown.
1- the project name is the same as a dependency that is used on the project
this error may happen when you choose a name for your project that is the same as one of the dependencies that you use on the project for example you cannot choose FirebaseAuth or GoogleSignIn as the project's name if you use them via pod or SPM.
to solve this problem you should change the project name with the following way:
choose the project from project navigator on the left sidebar, change the project name from the file inspector -> Identity and Type -> name from the right sidebar.
after you change it, XCode asks you to change all relative targets and just press rename.
2 - duplicated info.plist on the Copy Bundle resources portion
you may face this error when info.plist is added to Copy Bundle resources unwanted, choose project form project navigator -> choose target -> goto Build Phases tab -> Copy Bundle Resources and if you see info.plist there, remove it by choose info.plist like the following image
3 - pod files do not work well
sometimes you got this error because the dependencies that you use break for unexpected reasons.
1 - Delete Podfile.lock
2 - Delete Pods directory
3 - Delete Derived Data & Clean (you can find this directory from XCode menu -> Preferences... -> Locations -> Derived Data and go to the directory by clicking the arrow icon at the right of the address)
4 - Exit Xcode
5 - Update CocoaPods with [sudo] gem install cocoapods on mac terminal
6 - goto the project directory on the terminal and run pod install
7 - Open workspace and build
5- duplicated Core data
you may face this problem when you use Core data on the project
first I explain coreData codegen types:
**Class Definition: ** Choose Class Definition when you don’t need to edit the properties or functionality of the managed object subclass and properties files that Core Data generates for you.
Category/Extension: Choose Category/Extension to add additional convenience methods or business logic inside your managed object subclass.
Manual/None: Choose Manual/None to edit the properties in your managed object subclass, for example, to alter access modifiers, and to add additional convenience methods or business logic.
Choose the Manual/None and check if a copy of xcmodeldata is exist on CopyBundleRecources, remove it.
Well, in my case:
If you create two file with same name, will trigger this error.
Remove the one you recently added, will solve this problem.
Hope this helps.
I had this problem when I had a file with the same name in two different targets. For some reason one of those files I had part of both targets. So basically I had two files. And both of those files belonged to one target.
It makes sense that a target can only have one file name per target, so just unchecking the target member box for the file that wasn't related to the main target fixed the issue.
So the problem I was having is that I had accidentally included the Info.plist in the project settings -> Build Phases -> Copy Bundle Resources for my target.
Steps:
Go to Xcode File
Click to WorkSpace Settings
Build System Select as Legacy Build System
Here is another working solution : (If you are using custom Pods)
Select "Pods" from sidebar as highlights in screenshot.
Click on Build Phase. Expand "Headers" section. There are 3 options Public, Private, Project
Expand Public and check there are duplicate files. Remove it. DONE!!
Unfortunately none of these answers worked for me... here was the error I was seeing:
"Multiple commands produce '/Users/.../.../.../Frameworks/abcdef.framework"
That command depends on command ...: script phase ""
That command depends on command ...: script phase ""
Adding this line to the Podfile and doing a " Pod Install " was the ONLY thing that worked.
install! 'cocoapods', :disable_input_output_paths => true
I really hope this helps someone. I spent hours trying to fix this and finally got it.
Sometimes I just wish Xcode was as efficient as IntelliJ / Android Studio :(
Goodluck!
My error was:
duplicate output file
'/Users/home/Library/Developer/Xcode/DerivedData/myAppName-fawptgabysjowicvpeqydjniuovo/Build/Products/Debug-iphoneos/myAppName.app/GoogleMaps.bundle'
on task: PhaseScriptExecution [CP] Copy Pods Resources
/Users/home/Library/Developer/Xcode/DerivedData/myAppName-fawptgabysjowicvpeqydjniuovo/Build/Intermediates.noindex/myAppName.build/Debug-iphoneos/myAppName.build/Script-32CCC25BF727B592A1784900.sh
I focused on the problem file being GoogleMaps.bundle and the location of that file being in [CP] Copy Pods Resources, and the fact that it specified it’s a duplicate output file (I highlighted them in black above), it's the 4th step below
First create a copy of your project and make sure you first do the following steps on that copy
1- In the project navigator I went to the blue project icon
2- I choose Build phases
3- Under Build Phases I choose [CP] Copy Pods Resources
4- Under [CP] Copy Pods Resources I went to Output Files and underneath there I found the file that ended with GoogleMaps.bundle. I selected it and pressed the minus sign to delete it. Make sure you go to Output Files and NOT Input Files
5- I did a clean shift+cmmd+k and afterwards when I built the project the error was gone
The odd thing was even though the red error went away the yellow warning was still there but it worked :)
I had bunch of Multiple commands produce warnings - not limited to info.plist duplication in one target. Including localized resources and string files, headers etc.
Solution: remove all duplications in target membership.
Try all this option anyone of this 3 option will work for you, for sure
Option 1: Remove all files from
Target >> Build Phases >> Compile Sources
Target >> Build Phases >> Copy Bundle Resources
Option 2: Change the build system
Xcode->File->Project Settings-> Build System -> Legacy Build System
Option 3: remove and update existing pod
pod cache clean PromisesObjC
pod cache clean PromisesSwift
cd [your_project_dir]
rm -rf Pods/
rm Podfile.lock
pod update
I hope this will help you, Happy coding :-)
Go in Project Build Phase and Remove info.plist from the Compile Sources. It will remove that issue and project will be active again.
It's worth noting that this error can be produced after auto generation of CoreData models where the Codegen is not set to Manual/None.
To correct this in Xcode 10 double click on your xcdatamodeId file and select each of your entities and set Codegen to Manual/None under Class in your Data Model Inspector.
I'm trying to add some new resource files to a project which was build by another person on another mac. I think that the project has the provision of the previous person.
Using right click->Add Files to "MyProject" doesn't provide the expected result. After I compile the project, the added file is not visible in the application.
How can I add new resources in my project?
PS: I'm trying to learn Objective-C in a macincloud.com account.
It might be that the file you added was not added to the project build. Click your project > App target > Build Phases
And check that the file exists in Compile sources (if it needs to be compiled), otherwise check Copy bundle resources. If the file does not exist there, drag it there and it should be fine, (from what I understand of your question).
EDIT
You can also check wether a file is added to the target by clicking the file and opening the "File Inspector" (View > Utilities > Show File Inspector, or ⌥ + ⌘ + 1), and check the Target Membership section.
Example:
Adding to Copy bundle resources worked for me
Just drag the resource file (from a finder window) into your project files area (left side) and drop in supporting files.
Once you drop, a dialog will prompt you which targets to add it for. Select all that are appropriate. Thats it.
Just had a similar experience with Xcode Version 11.7 (11E801a), which I mention as it may help others from wasting a day and a half.
In addition to the other answers explaining how to add the resources:
For me the problem was I had my resources listed in Developer Assets under the target's General tab, but also in the Build Phases/Copy Bundle Resources. This worked fine running through Xcode in simulators and even on devices, but when I came to Archive the app, the resources were not being copied. Deleting my resources from the Developer Assets list, but keeping them in Build Phases worked.
And in the end it turns out I only need the resources in the Build Phases section for either running through XCode or Archiving !
I'm trying to embed a private framework (last paragraph) in my application bundle using XCode 4 and following Apple's (seemingly) outdated instructions.
In my case, I'm Using Separate Xcode Projects For Each Target. This is the final step:
In the General tab of the inspector window, add your framework as a dependency for the application. Adding this dependency causes Xcode to
build the framework target before building the application target.
The build dependency you establish in the application target causes the framework to be built before the application. This is important because it guarantees that a built version of your framework will be available to link against and to embed in the application. Because of this dependency, you can set the active target of your Xcode project to your application and leave it there. Building the application now builds the framework and copies it to the application bundle directory, creating the necessary linkage between the two.
Yet, when in click on the + button in Target Dependencies the framework doesn't show up. How can I establish a build dependency between the private framework and the application target in Xcode 4?
Edit: I should clarify that I already got the private framework working. I just want to avoid having cleaning the project every time a change to the framework is made, and make sure the framework is built before the application target.
Managed to solve this by adding the private framework project as a subproject, then adding the framework target in Target Dependencies.
However, in my case the framework target didn't show as an option in Target Dependencies until I deleted DerivedData. That nasty little bug drove me crazy.
If you want to add your private framework without including it as a sub project, you have to add a Copy Files task for it:
Select your framework with the + button and choose Frameworks for Destination.
You don't need to add anything in Target Dependencies.
Also for this to work, make sure Runpath Search Paths value is #executable_path/Frameworks in the Build Settings tab.
Select your project in the Xcode and then you can find the Project and Target at the right side. Then Select Target and go to LinkBinary with Libraries and then one window will come and there at the bottom left there is an option called Add other.
You first need to add the other project's .xcodeproj to the project as a subproject:
Right-click the Frameworks group (or whatever/wherever else)
Select Add Files to "<Project>..."
Select the other project's .xcodeproj
That other project's targets will now appear in the Target Dependencies menu
Here is more complete answer with update for Xcode 12+.
Copy the 3rd party framework to your project folder.
It can be anywhere within the same project in the tree. You will need the path info in later steps.
In Xcode, select your build target, then select "general" tab, scroll down to "Framework, libraries, and Embedded Content", then select "+" to browse and select the 3rd part library/framework you want to add. See bellow:
Once added, make sure "Embed & Sign" is selected at the dropdown list for the library/framework you are trying to add.
This is important since the framework will be looked up and loaded at runtime.
Go to "Build Settings" tab, and find "Framework Search Path", and enter the path to the framework's in relative to your Xcode project file's location. See bellow:
Now you can build and run your app with the added framework.
I'm trying to add some new resource files to a project which was build by another person on another mac. I think that the project has the provision of the previous person.
Using right click->Add Files to "MyProject" doesn't provide the expected result. After I compile the project, the added file is not visible in the application.
How can I add new resources in my project?
PS: I'm trying to learn Objective-C in a macincloud.com account.
It might be that the file you added was not added to the project build. Click your project > App target > Build Phases
And check that the file exists in Compile sources (if it needs to be compiled), otherwise check Copy bundle resources. If the file does not exist there, drag it there and it should be fine, (from what I understand of your question).
EDIT
You can also check wether a file is added to the target by clicking the file and opening the "File Inspector" (View > Utilities > Show File Inspector, or ⌥ + ⌘ + 1), and check the Target Membership section.
Example:
Adding to Copy bundle resources worked for me
Just drag the resource file (from a finder window) into your project files area (left side) and drop in supporting files.
Once you drop, a dialog will prompt you which targets to add it for. Select all that are appropriate. Thats it.
Just had a similar experience with Xcode Version 11.7 (11E801a), which I mention as it may help others from wasting a day and a half.
In addition to the other answers explaining how to add the resources:
For me the problem was I had my resources listed in Developer Assets under the target's General tab, but also in the Build Phases/Copy Bundle Resources. This worked fine running through Xcode in simulators and even on devices, but when I came to Archive the app, the resources were not being copied. Deleting my resources from the Developer Assets list, but keeping them in Build Phases worked.
And in the end it turns out I only need the resources in the Build Phases section for either running through XCode or Archiving !
Is there an easy way of getting Three20 v1.1 to work under xCode 4?
I followed the steps on http://three20.info/article/2011-03-10-Xcode4-Support but that seems to be for the master. I use v1.1 as I use the TTLauncher.
The project builds fine with a normal build, and runs perfect on an iPhone.
But when I want to create the archive (for the IPA for distribution) then I get 18 errors and 8 warnings.
The first one is:
../scripts/Protect.command: line 23: cd: /Users/XXX/Library/Developer/Xcode/DerivedData/iDoms-cmyivarwxpbvqdfnyclqdrikrtmw/ArchiveIntermediates/iDoms/BuildProductsPath/Release-iphoneos/../three20/Three20UICommon: No such file or directory
Most others are 'no such file or directory' on e.g.:
#import "Three20Core/TTGlobalCoreLocale.h"
or 'undeclared (first use of function)' which comes from the 'no such file or directory issue I presume'.
In my 'Header search paths' I have:
$(BUILT_PRODUCTS_DIR)/../three20
$(BUILT_PRODUCTS_DIR)/../../three20
../../three20/Build/Products/three20
/usr/include/libxml2
Any help would be very appreciated!
Just to add to Colin's answer: you can use Xcode's dependent projects feature to use three20, even though the three20 website says it's not "officially supported":
In your workspace, right-click on the empty space in your project navigator. Select "Add files to "My Workspace", and select the three20 project (three20/src/Three20/Three20.xcodeproj). This is the only project you need to add: it is not necessary to manually add the three20 subprojects.
Select your project in the navigator, go to Build Phases, open "Link binary with libraries", click on the "+" in the bottom left corner, and add the Three20 libraries: libThree20.a, libThree20Core.a, libThree20Network.a, libThree20Style.a, libThree20UI.a, libThree20UICommon.a and libThree20Navigator.a. This will cause Xcode to build Three20 when you build your project.
Add ${BUILD_DIR}/three20 to your include path as per Colin's answer: go to build settings, double click on "Header Search Paths", and add ${BUILD_DIR}/three20 (it will show as build/three20 when you close the dialog).
Add three20/src/Three20.bundle to your resources.
It's probably also a good idea to add the linker flags -ObjC and -all_load if you haven't already done so (same dialog, setting "Other Linker Flags").
The steps above are good enough for compiling the code. To make "Archive" work too, you will need to:
Add $(BUILT_PRODUCTS_DIR)/../three20 and $(BUILT_PRODUCTS_DIR)/../../three20 to the Header Search Paths setting. If you don't you will get compilation errors that the three20 headers cannot be found.
For all Three20 projects (so not just the top-level project), go the Build Settings and set "Skip Install" to YES. If you don't, the project will build, but you will not be able to create an IPA.
Make sure that your product name (select your target, go to Build Settings, then setting "Product Name") does not contain spaces, otherwise archiving will not work.
Finally, if you're getting errors such as ld: library not found for -lThree20 and you are using a custom build configuration (such as AdHoc), make sure to add the same build configuration to each of the Three20 projects too (just duplicate the Release configuration).
You should check out this StackOverflow question.
I've reproduced the accepted answer below:
So it looks like the easiest way
to get old Xcode 3.2 projects to work
with Xcode 4 is to do the following:
Go into Xcode 4's preferences (Cmd+,).
Select the "Locations" tab. Where it
says "Build Locations", select the
drop down and pick "Place build
products in locations specified by
targets" I'll write up a three20.info
article going into more details about
this.
Add these two paths to your header search paths in the build settings for your target:
"$(BUILD_DIR)/three20"
"$(BUILD_DIR)/../three20"
The first entry is needed for regular builds and the second entry is needed for archives.
It's that easy.
Incidentally, to create a file in your home directory with a list of all of Xcode's environment variables for your target's environement, add the following Run script build phase to your target with contents:
ENV > ~/xcode-environment.sh
Note that in this case, if your project is not making it through the compile phase of the build process, and your Run script comes later, the script won't get executed, so put it first.