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I've been researching the build process of an iOS app. I created a "Single view application" project and built in Xcode 8.2.1. While I was looking at the build report, I noticed Xcode compiles and links .m files using clang, and then compiles and links storyboard files using ibtool. I am wondering what is ibtool actually doing in the compiling and linking process. After the following compiling command, .storyboardc files are created at /Users/Kazu/Library/Developer/Xcode/DerivedData/ObjCHelloWorld-guewhpmwckompbfvsbhizkifcadg/Build/Intermediates/ObjCHelloWorld.build/Debug-iphonesimulator/ObjCHelloWorld.build/Base.lproj/ directory, which will be used in later in "Link Storyboards" phase. .storyboardc files were a bundle of binaries including Info.plist file.

 ObjCHelloWorld/Base.lproj/LaunchScreen.storyboard
cd /Users/Kazu/Dropbox/ObjCHelloWorld
export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"
export XCODE_DEVELOPER_USR_PATH=/Applications/Xcode.app/Contents/Developer/usr/bin/..
/Applications/Xcode.app/Contents/Developer/usr/bin/ibtool --errors --warnings --notices --module ObjCHelloWorld --output-partial-info-plist /Users/Kazu/Library/Developer/Xcode/DerivedData/ObjCHelloWorld-guewhpmwckompbfvsbhizkifcadg/Build/Intermediates/ObjCHelloWorld.build/Debug-iphonesimulator/ObjCHelloWorld.build/LaunchScreen-SBPartialInfo.plist --auto-activate-custom-fonts --target-device iphone --target-device ipad --minimum-deployment-target 10.2 --output-format human-readable-text --compilation-directory /Users/Kazu/Library/Developer/Xcode/DerivedData/ObjCHelloWorld-guewhpmwckompbfvsbhizkifcadg/Build/Intermediates/ObjCHelloWorld.build/Debug-iphonesimulator/ObjCHelloWorld.build/Base.lproj /Users/Kazu/Dropbox/ObjCHelloWorld/ObjCHelloWorld/Base.lproj/LaunchScreen.storyboard

In the linking phase, following command is executed, which I have no idea what ibtool is doing. All I can tell is it's using storyboardc files generated in the compile phase.

LinkStoryboards
cd /Users/Kazu/Dropbox/ObjCHelloWorld
export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"
export XCODE_DEVELOPER_USR_PATH=/Applications/Xcode.app/Contents/Developer/usr/bin/..
/Applications/Xcode.app/Contents/Developer/usr/bin/ibtool --errors --warnings --notices --module ObjCHelloWorld --target-device iphone --target-device ipad --minimum-deployment-target 10.2 --output-format human-readable-text --link /Users/Kazu/Library/Developer/Xcode/DerivedData/ObjCHelloWorld-guewhpmwckompbfvsbhizkifcadg/Build/Products/Debug-iphonesimulator/ObjCHelloWorld.app /Users/Kazu/Library/Developer/Xcode/DerivedData/ObjCHelloWorld-guewhpmwckompbfvsbhizkifcadg/Build/Intermediates/ObjCHelloWorld.build/Debug-iphonesimulator/ObjCHelloWorld.build/Base.lproj/LaunchScreen.storyboardc /Users/Kazu/Library/Developer/Xcode/DerivedData/ObjCHelloWorld-guewhpmwckompbfvsbhizkifcadg/Build/Intermediates/ObjCHelloWorld.build/Debug-iphonesimulator/ObjCHelloWorld.build/Base.lproj/Main.storyboardc

My question is, what is ibtool doing in the linking phase? Is there any product or it links to executable created in previous linking phase done by clang?

kazuochi
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1 Answers1

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Not sure if you've found the answer or mine will answer yours, but I'll post it anyway.

If you take a peak at compiled app (IPA files), you'll see your usual XIB files converted to NIB, and *.storyboard converted to *.storboardc (c should mean compiled). Then, if you open the xib or storyboard files with a text editor, you should see xml contents.

I believe ibtool does generate xml contents to user interface when you use xcode and view the xib / storyboard files. Then, when build, it generate to binary files (nib, storyboardc).

Linking phase should create a path to those compiled files and create a map or something like that. When you make a call to open those files, the app will find the path within the map and get the expected nib file for you, in a specific bundle (usually main bundle, which is at the root of the compiled app folder).

PS: That's probably why the method is call: initWithNibName, not initWithXibName

Eddie
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