Building an iOS App Without Xcode’s Build System by Vojta Stavik

The App We’re About to Build

I let Xcode 10.0 generate a new project using the Single View App template, and named it “ExampleApp”. This is going to be the reference app we will try to build “manually”. The only adjustment to the project I made was adding a UILabel with ???? to the main (and only) ViewController.

I also created the build.bash file in the root folder of the project. We’re going use this file for the actual build script.

Don’t forget to make the file executable by running the following in the terminal:

$ chmod +x build.bash

Step 1: Prepare Working Folders

⚠️ Disclaimer 2 ⚠️

The complete “recipe” of how the app should be built is contained in its xcodeproj file. This article is not about how to parse and retrieve this information from it.

We will ignore the project file for the sake of this article. To make our life easier, we will hard-code all the details like the project name, source files, or build settings, directly into the build script.

Let’s start with some housekeeping. We need to define and create a set of folders we will be using during the building process.

#############################################################
# build.bash
############################################################# #!/bin/bash # Exit this script immediately if any of the commands fails
set -e PROJECT_NAME=ExampleApp # The product of this script. This is the actual app bundle!
BUNDLE_DIR=${PROJECT_NAME}.app # A place for temporary files needed for building
TEMP_DIR=_BuildTemp #############################################################
echo → Step 1: Prepare Working Folders
############################################################# # Delete existing folders from previous builds
rm -rf ${BUNDLE_DIR}
rm -rf ${TEMP_DIR} mkdir ${BUNDLE_DIR}
echo ✅ Create ${BUNDLE_DIR} folder mkdir ${TEMP_DIR}
echo ✅ Create ${TEMP_DIR} folder

When you run the script, your terminal should like this:

$ ./build.bash
→ Step 1: Prepare Working Folders
✅ Create ExampleApp.app folder
✅ Create _BuildTemp folder

Notice, that the script created two folders:

Step 2: Compile Swift Files

Did you know you can call the Swift compiler directly from the terminal using swiftc?

$ swiftc -h
OVERVIEW: Swift compiler USAGE: swiftc [options] <inputs>
...

With the correct flags, compiling all .swift source files is quite a straightforward operation.

#############################################################
echo → Step 2: Compile Swift Files
############################################################# # The root directory of the project sources
SOURCE_DIR=ExampleApp # All Swift files in the source directory
SWIFT_SOURCE_FILES=${SOURCE_DIR}/*.swift # Target architecture we want to build for
TARGET=x86_64-apple-ios12.0-simulator # Path to the SDK we want to use for compiling
SDK_PATH=$(xcrun --show-sdk-path --sdk iphonesimulator) swiftc ${SWIFT_SOURCE_FILES} \
  -sdk ${SDK_PATH} \
  -target ${TARGET} \
  -emit-executable \
  -o ${BUNDLE_DIR}/${PROJECT_NAME} echo ✅ Compile Swift source files ${SWIFT_SOURCE_FILES}

I’d like to talk a little bit about the -emit-executable flag. According to the documentation, when this flag is used, the compiler “emits a linked executable”. When you run swiftc in the verbose mode (-v), you can actually see, what’s happening under the hood. The compiler creates .oobject for every .swift file, and then calls ld to link them into the final executable file.

Notice, that we set output (-o) to ExampleApp.app/ExampleApp. That’s the resulting executable file from the compilation process.

Run the script and you should see the following:

$ ./build.bash
→ Step 1: Prepare Working Folders
✅ Create ExampleApp.app folder
✅ Create _BuildTemp folder → Step 2: Compile Swift Files
✅ Compile Swift source files ExampleApp/AppDelegate.swift ExampleApp/ViewController.swift

You can also check, that the resulting executable was created inside the ExampleApp.app bundle:

$ tree ExampleApp.app
ExampleApp.app
└── ExampleApp

Step 3: Compile Storyboards

Source code files are not the only files which need to be compiled. We also need to compile all .storyboard files. The compiler for storyboards (and all the other interface builder files) is called ibtool. The resulting files from the process have the extension .storyboardc.

Fun fact

storyboardc files are file bundles. When you inspect the content of the bundle, you will see, that a compiled storyboard is actually just a bunch of nib files.

ibtool doesn’t accept more than one file at a time. We need to use a for loop to iterate over all storyboards.

#############################################################
echo → Step 3: Compile Storyboards
############################################################# # All storyboards in the Base.lproj directory
STORYBOARDS=${SOURCE_DIR}/Base.lproj/*.storyboard # The output folder for compiled storyboards
STORYBOARD_OUT_DIR=${BUNDLE_DIR}/Base.lproj mkdir -p ${STORYBOARD_OUT_DIR}
echo ✅ Create ${STORYBOARD_OUT_DIR} folder for storyboard_path in ${STORYBOARDS}; do
  #
  ibtool $storyboard_path \
    --compilation-directory ${STORYBOARD_OUT_DIR}   echo ✅ Compile $storyboard_path
done

Let’s run the script and verify the content of ExampleApp.app:

$ ./build.bash
→ Step 1: Prepare Working Folders
✅ Create ExampleApp.app folder
✅ Create _BuildTemp folder → Step 2: Compile Swift Files
✅ Compile Swift source files ExampleApp/AppDelegate.swift ExampleApp/ViewController.swift → Step 3: Compile Storyboards
✅ Create ExampleApp.app/Base.lproj folder
✅ Compile ExampleApp/Base.lproj/LaunchScreen.storyboard
✅ Compile ExampleApp/Base.lproj/Main.storyboard $ tree -L 2 ExampleApp.app
ExampleApp.app
├── Base.lproj
│   ├── LaunchScreen.storyboardc
│   └── Main.storyboardc
└── ExampleApp

Step 4: Process and Copy Info.plist

A valid app bundle has to contain Info.plist. Unfortunately, we can’t simply copy the one from the project directory. This raw file contains several variables which we need to replace with the actual values.

Info.plist variables
----------------------------------------------
<key>CFBundleExecutable</key>
<string>$(EXECUTABLE_NAME)</string>
<key>CFBundleIdentifier</key>
<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
<key>CFBundleName</key>
<string>$(PRODUCT_NAME)</string>

To deal easily with plist files, Apple provides us with a tool called PlistBuddy. Because we don’t want to modify the original plist we first create a temporary copy in the _BuildTemp folder, and modify it there. Finally, we copy the processed plist to the app bundle.

#############################################################
echo → Step 4: Process and Copy Info.plist
############################################################# # The location of the original Info.plist file
ORIGINAL_INFO_PLIST=${SOURCE_DIR}/Info.plist # The location of the temporary Info.plist copy for editing
TEMP_INFO_PLIST=${TEMP_DIR}/Info.plist # The location of the processed Info.plist in the app bundle
PROCESSED_INFO_PLIST=${BUNDLE_DIR}/Info.plist # The bundle identifier of the resulting app
APP_BUNDLE_IDENTIFIER=com.vojtastavik.${PROJECT_NAME} cp ${ORIGINAL_INFO_PLIST} ${TEMP_INFO_PLIST}
echo ✅ Copy ${ORIGINAL_INFO_PLIST} to ${TEMP_INFO_PLIST}

 # A command line tool for dealing with plists
PLIST_BUDDY=/usr/libexec/PlistBuddy # Set the correct name of the executable file we created at step 2
${PLIST_BUDDY} -c "Set :CFBundleExecutable ${PROJECT_NAME}" ${TEMP_INFO_PLIST}
echo ✅ Set CFBundleExecutable to ${PROJECT_NAME} # Set a valid bundle indentifier
${PLIST_BUDDY} -c "Set :CFBundleIdentifier ${APP_BUNDLE_IDENTIFIER}" ${TEMP_INFO_PLIST}
echo ✅ Set CFBundleIdentifier to ${APP_BUNDLE_IDENTIFIER} # Set the proper bundle name
${PLIST_BUDDY} -c "Set :CFBundleName ${PROJECT_NAME}" ${TEMP_INFO_PLIST}
echo ✅ Set CFBundleName to ${PROJECT_NAME} # Copy processed Info.plist to the app bundle
cp ${TEMP_INFO_PLIST} ${PROCESSED_INFO_PLIST}
echo ✅ Copy ${TEMP_INFO_PLIST} to ${PROCESSED_INFO_PLIST}

Let’s run the script:

$ ./build.bash
# ... #
→ Step 4: Process and Copy Info.plist
✅ Copy ExampleApp/Info.plist to _BuildTemp/Info.plist
✅ Set CFBundleExecutable to ExampleApp
✅ Set CFBundleIdentifier to com.vojtastavik.ExampleApp
✅ Set CFBundleName to ExampleApp
✅ Copy _BuildTemp/Info.plist to ExampleApp.app/Info.plist

We should also verify that the processed plist file is there, and its content is correct:

$ cat ExampleApp.app/Info.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "https://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  # ... #
    <key>CFBundleExecutable</key>
    <string>ExampleApp</string>
    <key>CFBundleIdentifier</key>
    <string>com.vojtastavik.ExampleApp</string>
    <key>CFBundleInfoDictionaryVersion</key>
    <string>6.0</string>
    <key>CFBundleName</key>
    <string>ExampleApp</string>
  # ... #
</dict>
</plist>

Running ExampleApp in the Simulator

At this point, we should have a valid .app bundle. At least for running it in the iOS simulator. You can open the simulator directly from the terminal window:

$ open -a "Simulator.app"

To interact with iOS simulators, Apple created a tool named simctl. Here’s how you can install the ExampleApp app bundle to the currently running simulator. The second command starts the installed app.

$ xcrun simctl install booted ExampleApp.app

$ xcrun simctl launch booted com.vojtastavik.ExampleApp

I must admit I was extremely surprised when I saw the app was working!

The truth is, I thought one more step would be needed. Swift doesn’t have a stable binary interface yet and Swift runtime is not included in iOS. Thus every app has to have its own copy of the Swift runtime libraries included in the bundle.

We haven’t copied the runtime libraries into the bundle but the app works!

When compiling Swift files using swiftc, you can specify a dylib runtime search folder using -Xlinker -rpathflags. By doing so, you’re letting the linker know where to search for dynamic libraries, like the Swift-runtime ones. It turns out if you don’t specify them as I did, the search path defaults to:

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator

This is exactly the place where the Swift runtime libraries are stored on your computer!

The iOS simulator is not sandboxed and has access to all your files. It means it can easily load the runtime libraries from any arbitrary place. I had no idea about this.

As long as you target the iOS simulator, you can create a valid, fully functional, Swift iOS app without including the Swift runtime libs in the bundle.

Building for Device

As you can see, building for Simulator is quite forgiving. We don’t need to include the runtime libraries in the bundle. We also don’t need to sign it and deal with provisioning.

Changing the build script so it can produce a valid app bundle, which can be executed on an iOS device, is another level of fun.

Firstly, we need to let the script know when to build for device.

Let’s use the --device flag to signal the script the desired target architecture. We update the code from step 1:

#############################################################
#  build.bash
############################################################# #!/bin/bash # Exit this script immediately if any of the commands fails
set -e PROJECT_NAME=ExampleApp # The product of this script. This is the actual app bundle!
BUNDLE_DIR=${PROJECT_NAME}.app # A place for any temporary files needed for building
TEMP_DIR=_BuildTemp # Check for --device flag
if [ "$1" = "--device" ]; then                            #
  BUILDING_FOR_DEVICE=true;                               #
fi                                                        #
                                                          #
# Print the current target architecture
if [ "${BUILDING_FOR_DEVICE}" = true ]; then              #
  echo ???? Building ${PROJECT_NAME} for device             #
else                                                      #
  echo ???? Building ${PROJECT_NAME} for simulator          #
fi                                                        # #############################################################
echo → Step 1: Prepare Working Folders
#############################################################
...

Secondly, we need to update the code from step 2:

#############################################################
echo → Step 2: Compile Swift Files
############################################################# # The root directory of the project sources
SOURCE_DIR=ExampleApp # All Swift files in the source directory
SWIFT_SOURCE_FILES=${SOURCE_DIR}/*.swift # Target architecture we want to build for
TARGET="" # Path to the SDK we want to use for compiling
SDK_PATH="" if [ "${BUILDING_FOR_DEVICE}" = true ]; then
  # Building for device
  TARGET=arm64-apple-ios12.0
  SDK_PATH=$(xcrun --show-sdk-path --sdk iphoneos) # The folder inside the app bundle where we
  # will copy all required dylibs
  FRAMEWORKS_DIR=Frameworks # Set additional flags for the compiler
  OTHER_FLAGS="-Xlinker -rpath -Xlinker @executable_path/${FRAMEWORKS_DIR}" else
  # Building for simulator
  TARGET=x86_64-apple-ios12.0-simulator
  SDK_PATH=$(xcrun --show-sdk-path --sdk iphonesimulator)
fi # Compile sources
swiftc ${SWIFT_SOURCE_FILES} \
  -sdk ${SDK_PATH} \
  -target ${TARGET} \
  -emit-executable \
  ${OTHER_FLAGS} \
  -o ${BUNDLE_DIR}/${PROJECT_NAME} echo ✅ Compile Swift source files ${SWIFT_SOURCE_FILES}

Changes we made:

• We check the value of BUILDING_FOR_DEVICE and set TARGET and SDK_PATHvariables accordingly.
• We introduced the OTHER_FLAGS variable. This variable is empty for simulator builds. For device builds, we pass to the compiler additional information about where to find dynamic libraries in the app bundle. For device builds, we will HAVE TO include Swift runtime in the app bundle.

Finally:

Because all the next steps will be needed only for device builds, if we build for simulator, we can exit the build script right after step 4.

Let’s add this to the end of the script:

#############################################################
if [ "${BUILDING_FOR_DEVICE}" != true ]; then
  # If we build for simulator, we can exit the scrip here
  echo ???? Building ${PROJECT_NAME} for simulator successfully finished! ????
  exit 0
fi
#############################################################

Step 5: Copy Swift Runtime Libraries

I already mentioned, when building for device, we need to include the Swift runtime libraries in the app bundle. Fortunately, no magic is required here. We can just simply copy the libraries to the bundle.

#############################################################
echo → Step 5: Copy Swift Runtime Libraries
############################################################# # The folder where the Swift runtime libs live on the computer
SWIFT_LIBS_SRC_DIR=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphoneos # The folder inside the app bundle where we want to copy them
SWIFT_LIBS_DEST_DIR=${BUNDLE_DIR}/${FRAMEWORKS_DIR} # The list of all libs we want to copy
SWIFT_RUNTIME_LIBS=( libswiftCore.dylib libswiftCoreFoundation.dylib libswiftCoreGraphics.dylib libswiftCoreImage.dylib libswiftDarwin.dylib libswiftDispatch.dylib libswiftFoundation.dylib libswiftMetal.dylib libswiftObjectiveC.dylib libswiftQuartzCore.dylib libswiftSwiftOnoneSupport.dylib libswiftUIKit.dylib libswiftos.dylib ) mkdir -p ${BUNDLE_DIR}/${FRAMEWORKS_DIR}
echo ✅ Create ${SWIFT_LIBS_DEST_DIR} folder for library_name in "${SWIFT_RUNTIME_LIBS[@]}"; do
  # Copy the library
  cp ${SWIFT_LIBS_SRC_DIR}/$library_name ${SWIFT_LIBS_DEST_DIR}/
  echo ✅ Copy $library_name to ${SWIFT_LIBS_DEST_DIR}
done

Let’s run the script and verify the result. Don’t forget to use --device.

$ ./build.bash --device
???? Bulding ExampleApp for device
# ... #
→ Step 5: Copy Swift Runtime Libraries
✅ Copy libswiftCore.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftCoreFoundation.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftCoreGraphics.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftCoreImage.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftDarwin.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftDispatch.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftFoundation.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftMetal.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftObjectiveC.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftQuartzCore.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftSwiftOnoneSupport.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftUIKit.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftos.dylib to ExampleApp.app/Frameworks $ tree -L 2 ExampleApp.app
ExampleApp.app
├── Base.lproj
│   ├── LaunchScreen.storyboardc
│   └── Main.storyboardc
├── ExampleApp
├── Frameworks
│   ├── libswiftCore.dylib
│   ├── libswiftCoreFoundation.dylib
│   ├── libswiftCoreGraphics.dylib
│   ├── libswiftCoreImage.dylib
│   ├── libswiftDarwin.dylib
│   ├── libswiftDispatch.dylib
│   ├── libswiftFoundation.dylib
│   ├── libswiftMetal.dylib
│   ├── libswiftObjectiveC.dylib
│   ├── libswiftQuartzCore.dylib
│   ├── libswiftSwiftOnoneSupport.dylib
│   ├── libswiftUIKit.dylib
│   └── libswiftos.dylib
└── Info.plist

Step 6: Code Signing

I spent over 20 hours trying to figure out all the steps needed to successfully build the app for device. A half of this time I spent on this one step.

Before we start, here’s a nice picture of kittens for you.

6.1 Provisioning Profile

All your installed provisioning profiles are stored in ~/Library/MobileDevice/Provisioning\ Profiles/. The first challenge is to find the correct one to use for this app.

I’d strongly recommend to figure everything out in Xcode, first. If I’m not mistaken, with the free Apple dev account, you can’t even create a new provisioning profile using the web portal. You have to use Xcode for that.

Once you have the code signing working there, make a note of which provisioning profile and signing identity were used.

For the app bundle to be valid, it has to contain a file named embedded.mobileprovision in its root. Let’s copy the correct provisioning profile to the app bundle, and rename it:

#############################################################
echo → Step 6: Code Signing
############################################################# # The name of the provisioning file to use
# ⚠️ YOU NEED TO CHANGE THIS TO YOUR PROFILE ️️⚠️
PROVISIONING_PROFILE_NAME=23a6e9d9-ad3c-4574-832c-be6eb9d51b8c.mobileprovision # The location of the provisioning file inside the app bundle
EMBEDDED_PROVISIONING_PROFILE=${BUNDLE_DIR}/embedded.mobileprovision cp ~/Library/MobileDevice/Provisioning\ Profiles/${PROVISIONING_PROFILE_NAME} ${EMBEDDED_PROVISIONING_PROFILE}
echo ✅ Copy provisioning profile ${PROVISIONING_PROFILE_NAME} to ${EMBEDDED_PROVISIONING_PROFILE}

6.2 Signing Entitlements

Another file needed to successfully sign the bundle is the .xcent file. This file is just another plist, created by merging project’s Entitlements file with additional signing information.

There’s no Entitlements file in our project, so this part of merging is done ????.

The additional signing information, I was referring to, is the Apple dev team ID. This ID has to be the one from the signing identity you are about to use in the next step.

Let’s create the .xcent file and set the required values:

#############################################################
echo → Step 6: Code Signing
############################################################# ... # The team identifier of your signing identity
# ⚠️ YOU NEED TO CHANGE THIS TO YOUR ID ️️⚠️
TEAM_IDENTIFIER=X53G3KMVA6 # The location if the .xcent file
XCENT_FILE=${TEMP_DIR}/${PROJECT_NAME}.xcent # The file doesn't exist but PlistBuddy will create it automatically
${PLIST_BUDDY} -c "Add :application-identifier string ${TEAM_IDENTIFIER}.${APP_BUNDLE_IDENTIFIER}" ${XCENT_FILE}
${PLIST_BUDDY} -c "Add :com.apple.developer.team-identifier string ${TEAM_IDENTIFIER}" ${XCENT_FILE} echo ✅ Create ${XCENT_FILE}

6.3 Signing

Now, when we have all the required pieces in place, we perform the actual signing. The tool which will help us with this is called codesign.

You need to specify which identity should be used for signing. You can list all available identities in the terminal using:

$ security find-identity -v -p codesigning

For the app bundle to be valid, we need to sign all dynamic libraries in the Frameworks folder, and then the bundle itself. We use the xcent file only for the final signing. Let’s finish this!

#############################################################
echo → Step 6: Code Signing
############################################################# ... # The id of the identity used for signing
IDENTITY=E8C36646D64DA3566CB93E918D2F0B7558E78BAA # Sign all libraries in the bundle
for lib in ${SWIFT_LIBS_DEST_DIR}/*; do
  # Sign
  codesign \
    --force \
    --timestamp=none \
    --sign ${IDENTITY} \
    ${lib}
  echo ✅ Codesign ${lib}
done # Sign the bundle itself
codesign \
  --force \
  --timestamp=none \
  --sign ${IDENTITY} \
  --entitlements ${XCENT_FILE} \
  ${BUNDLE_DIR} echo ✅ Codesign ${BUNDLE_DIR}

Celebrate!

The last part of the script we need to write is the final message:

#############################################################
echo ????Building ${PROJECT_NAME} for device successfully finished!????
exit 0
#############################################################

You can now run the script, sit back, and enjoy your victory:

$ ./build.bash --device
???? Building ExampleApp for device → Step 1: Prepare Working Folders
✅ Create ExampleApp.app folder
✅ Create _BuildTemp folder → Step 2: Compile Swift Files
✅ Compile Swift source files ExampleApp/AppDelegate.swift ExampleApp/ViewController.swift → Step 3: Compile Storyboards
✅ Create ExampleApp.app/Base.lproj folder
✅ Compile ExampleApp/Base.lproj/LaunchScreen.storyboard
✅ Compile ExampleApp/Base.lproj/Main.storyboard → Step 4: Process and Copy Info.plist
✅ Copy ExampleApp/Info.plist to _BuildTemp/Info.plist
✅ Set CFBundleExecutable to ExampleApp
✅ Set CFBundleIdentifier to com.vojtastavik.ExampleApp
✅ Set CFBundleName to ExampleApp
✅ Copy _BuildTemp/Info.plist to ExampleApp.app/Info.plist → Step 5: Copy Swift Runtime Libraries
✅ Create ExampleApp.app/Frameworks folder
✅ Copy libswiftCore.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftCoreFoundation.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftCoreGraphics.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftCoreImage.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftDarwin.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftDispatch.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftFoundation.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftMetal.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftObjectiveC.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftQuartzCore.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftSwiftOnoneSupport.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftUIKit.dylib to ExampleApp.app/Frameworks
✅ Copy libswiftos.dylib to ExampleApp.app/Frameworks → Step 6: Code Signing
✅ Copy provisioning profile 23a6e9d9-ad3c-4574-832c-be6eb9d51b8c.mobileprovision to ExampleApp.app/embedded.mobileprovision
File Doesn't Exist, Will Create: _BuildTemp/ExampleApp.xcent
✅ Create _BuildTemp/ExampleApp.xcent
ExampleApp.app/Frameworks/libswiftCore.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftCore.dylib
ExampleApp.app/Frameworks/libswiftCoreFoundation.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftCoreFoundation.dylib
ExampleApp.app/Frameworks/libswiftCoreGraphics.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftCoreGraphics.dylib
ExampleApp.app/Frameworks/libswiftCoreImage.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftCoreImage.dylib
ExampleApp.app/Frameworks/libswiftDarwin.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftDarwin.dylib
ExampleApp.app/Frameworks/libswiftDispatch.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftDispatch.dylib
ExampleApp.app/Frameworks/libswiftFoundation.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftFoundation.dylib
ExampleApp.app/Frameworks/libswiftMetal.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftMetal.dylib
ExampleApp.app/Frameworks/libswiftObjectiveC.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftObjectiveC.dylib
ExampleApp.app/Frameworks/libswiftQuartzCore.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftQuartzCore.dylib
ExampleApp.app/Frameworks/libswiftSwiftOnoneSupport.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftSwiftOnoneSupport.dylib
ExampleApp.app/Frameworks/libswiftUIKit.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftUIKit.dylib
ExampleApp.app/Frameworks/libswiftos.dylib: replacing existing signature
✅ Codesign ExampleApp.app/Frameworks/libswiftos.dylib
✅ Codesign ExampleApp.app ???? Building ExampleApp for device successfully finished! ????

Installing to an iOS Device

Unfortunately, installing the app to a connected iOS device is not at all that straightforward as it was for the simulator. Luckily, there are 3rd party tools which make the task much more pleasant.

I’m using ios-deploy.

You can list all connected devices using -c and then copy the identifier of the device.

$ ios-deploy -c
[....] Waiting up to 5 seconds for iOS device to be connected
[....] Found 00008020-xxxxxxxxxxxx (D321AP, D321AP, uknownos, unkarch) a.k.a. 'Vojta's iPhone' connected through USB.

Finally, you install the app bundle to the device using:

$ ios-deploy -i 00008020-xxxxxxxxxxxx -b ExampleApp.app

Next Steps

Here’s the GitHub repo with the final version of the script.

I learned a lot when writing this article. I don’t personally plan to work on this script anymore. However, if someone is interested in improving it, here are some ideas:

• I didn’t need to touch *.xcassets files because there was no content inside. However, these files also need to be compiled.
• It would be nice to get incremental builds working for Swift.
• The script currently builds only Swift files. What about projects with Objective-C, C++, Objective-C++, C sources?
• I don’t think it would make sense to parse xcodeprojand get the build parameters from it. What about getting the build settings from an XcodeGen file?
• What about target dependencies (like custom embedded frameworks) that also need to be built?

Special thanks to Harlan Haskins for helping me with the article by answering my questions.