Primary definitions
Initially you must have a transparent understanding in regards to the fundamental phrases. Should you already know what is the distinction between a module, package deal, library or framework you’ll be able to skip this part. Nevertheless in the event you nonetheless have some blended emotions about these items, please learn forward, you will not remorse it. 😉
Bundle
A package deal consists of Swift supply information and a manifest file.
A package deal is a group of Swift supply information. If you’re utilizing Swift Bundle Supervisor you even have to offer a manifest file so as to make an actual package deal. If you wish to be taught extra about this device, you must verify my Swift Bundle Supervisor tutorial.
Instance: that is your package deal:
Sources
my-source-file.swift
Bundle.swift
It’s also possible to take a look at the open sourced swift-corelibs-foundation package deal by Apple, which is used to construct the Basis framework for Swift.
Library
Library is a packaged assortment of object information that program can hyperlink towards.
So a library is a bunch of compiled code. You may create two sorts of libraries:
From a very easy perspective the one distinction between them is the tactic of “integrating” aka. linking them into your challenge. Earlier than I inform you extra about this course of, first we should always discuss object information.
Mach-O file format
To create packages, builders convert supply code to object information. The item information are then packaged into executable code or static libraries.
While you’re compiling the supply information you might be principally making object information, utilizing the Mach-O (MachObject) file format. These information are the core constructing blocks of your functions, frameworks, and libraries (each dynamic and static).
Linking libraries
Linking refers back to the creation of a single executable file from a number of object information.
In different phrases:
After the compiler has created all the article information, one other program known as to bundle them into an executable program file. That program known as a linker and the method of bundling them into the executable known as linking.
Linking is simply combining all of your object information into an executable and resolving all of the externals, so the system will be capable to name all of the capabilities contained in the binary.
Static linking
The supply code of the library is actually going to be copied into the appliance’s supply. This can end in an enormous executable, it’s going to take extra time to load, so the binary could have a slower startup time. Oh, did I point out that if you’re attempting to hyperlink the identical library greater than as soon as, the method will fail due to duplicated symbols?
This technique has benefits as nicely, for instance the executable will all the time include the right model of the library, and solely these elements shall be copied into the principle utility which can be actually used, so you do not have to load the entire stuff, however it looks like dynamic linking goes to be higher in some circumstances.
Dynamic linking
Dynamic libraries are usually not embedded into the supply of the binary, they’re loaded at runtime. Because of this apps could be smaller and startup time can considerably be sooner due to the light-weight binary information. As a free of charge dynamic libraries could be shared with a number of executables to allow them to have decrease reminiscence footprints. That is why typically they’re being referred as shared libraries.
After all if the dynamic library shouldn’t be accessible – or it is accessible however their model is incompatible – your utility will not run or it’s going to crash. Alternatively this may be a bonus, as a result of the creator of the dynamic library can ship fixes and your app can profit from these, with out recompilation.
Luckily system libraries like UIKit are all the time accessible, so you do not have to fret an excessive amount of about this subject…
Framework
A framework is a hierarchical listing that encapsulates shared sources, comparable to a dynamic shared library, nib information, picture information, localized strings, header information, and reference documentation in a single package deal.
So let’s make this straightforward: frameworks are static or dynamic libraries packed right into a bundle with some additional property, meta description for versioning and extra. UIKit is a framework which wants picture property to show among the UI parts, additionally it has a model description, by the way in which the model of UIKit is similar because the model of iOS.
Module
Swift organizes code into modules. Every module specifies a namespace and enforces entry controls on which elements of that code can be utilized outdoors of the module.
With the import key phrase you might be actually importing exterior modules into your sorce. In Swift you might be all the time utilizing frameworks as modules, however let’s return in time for some time to know why we wanted modules in any respect.
import UIKit
import my-awesome-moduleEarlier than modules you needed to import framework headers straight into your code and also you additionally needed to hyperlink manually the framework’s binary inside Xcode. The #import macro actually copy-pasted the entire resolved dependency construction into your code, and the compiler did the work on that vast supply file.
It was a fragile system, issues may go unsuitable with macro definitions, you possibly can simply break different frameworks. That was the explanation for outlining prefixed uppercased very lengthy macro names like: NS_MYSUPERLONGMACRONAME… 😒
There was an different subject: the copy-pasting resulted in non-scalable compile instances. With a purpose to remedy this, precompiled header (PCH) information have been born, however that was solely a partial answer, as a result of they polluted the namespace (you already know in the event you import UIKit in a PCH file it will get accessible in all over the place), and no-one actually maintained them.
Modules and module maps
The holy grail was already there, with the assistance of module maps (defining what sort of headers are a part of a module and what is the binary that has the implementation) we have got encapsulated modular frameworks. 🎉 They’re individually compiled as soon as, the header information are defining the interface (API), and the (mechanically) linked dylib file accommodates the implementation. Hurray, no have to parse framework headers throughout compilation time (scalability), so native macro definitions will not break something. Modules can include submodules (inheritance), and you do not have to hyperlink them explicitly inside your (Xcode) challenge, as a result of the .modulemap file has all the data that the construct system wants.
Finish of the story, now you already know what occurs below the hood, once you import Basis or import UIKit.
Command line instruments
Now that you already know the logic behind the entire dynamic modular framework system, we should always begin analyzing the instruments that make this infrastructure doable.
At all times learn the person pages, aka. RTFM! Should you do not wish to learn that a lot, you’ll be able to obtain the instance challenge from GitLab and open the makefiles for the essence. There shall be 3 fundamental classes: C, Swift and Xcode challenge examples.
clang
the Clang C, C++, and Goal-C compiler
Clang is a compiler frontend for C languages (C, C++, Goal-C). You probably have ever tried to compiled C code with gcc throughout your college years, you’ll be able to think about that clang is kind of the identical as gcc, however these days it could possibly do much more.
clang -c fundamental.c -o fundamental.o #compiles a C supply file
LLVM: compiler backend system, which might compile and optimize the intermediate illustration (IR) code generated by clang or the Swift compiler for instance. It is language impartial, and it could possibly achieve this many issues that would match right into a guide, however for now as an example that LLVM is making the ultimate machine code to your executable.
swiftc
The Swift compiler, there isn’t any guide entry for this factor, however don’t be concerned, simply fireplace up swiftc -h and see what can supply to you.
swiftc fundamental.swift #compiles a Swift supply file
As you’ll be able to see this device is what really can compile the Swift supply information into Mach-O’s or ultimate executables. There’s a quick instance within the connected repository, you must verify on that if you would like to be taught extra in regards to the Swift compiler.
ar
The ar utility creates and maintains teams of information mixed into an archive. As soon as an archive has been created, new information could be added and present information could be extracted, deleted, or changed.
So, in a nutshell you’ll be able to zip Mach-O information into one file.
ar -rcs myLibrary.a *.o
With the assistance of ar you have been capable of create static library information, however these days libtool have the identical performance and much more.
ranlib
ranlib generates an index to the contents of an archive and shops it within the archive. The index lists every image outlined by a member of an archive that may be a relocatable object file.
ranlib can create an index file contained in the static lib, so issues are going to be sooner once you’re about to make use of your library.
ranlib myLibrary.a
So ranlib & ar are instruments for sustaining static libraries, often ar takes care of the indexing, and you do not have to run ranlib anymore. Nevertheless there’s a higher possibility for managing static (and dynamic) libraries that you must be taught…
libtool
create libraries
With libtool you’ll be able to create dynamically linked libraries, or statically linked (archive) libraries. This device with the -static possibility is meant to switch ar & ranlib.
libtool -static *.o -o myLibrary.a
These days libtool is the principle possibility for build up library information, you must undoubtedly be taught this device in the event you’re into the subject. You may verify the instance challenge’s Makefile for more information, or as often you’ll be able to learn the manuals (man libtool). 😉
ld
The ld command combines a number of object information and libraries, resolves references, and produces an ouput file. ld can produce a ultimate linked picture (executable, dylib, or bundle).
Let’s make it easy: that is the linker device.
ld fundamental.o -lSystem -LmyLibLocation -lmyLibrary -o MyApp
It may hyperlink a number of information right into a single entity, so from the Mach-O’s you can make an executable binary. Linking is critical, as a result of the system must resolve the addresses of every technique from the linked libraries. In different phrases, the executable will be capable to run and all your capabilities shall be accessible for calling. 📱
nm
show title checklist (image desk)
With nm you’ll be able to see what symbols are inside a file.
nm myLibrary.a
# 0000000000001000 A __mh_execute_header
# U _factorial
# 0000000000001f50 T _main
# U _printf
# U dyld_stub_binder
As you’ll be able to see from the output, some type of reminiscence addresses are related for a few of symbols. People who have addresses are literally resolved, all of the others are coming from different libraries (they don’t seem to be resolved but). So which means they’re going to be resolved at runtime. The opposite possibility is that it’s a must to hyperlink them. 😅
otool
object file displaying device
With otool you’ll be able to study the contents of Mach-O information or libraries.
otool -L myLibrary.a
otool -tV myLibrary.a
For instance you’ll be able to checklist the linked libraries, or see the disassembled textual content contents of the file. It is a actually useful device in the event you’re conversant in the Mach-O file format, additionally good one to make use of for reverse-engineer an present utility.
lipo
create or function on common information
With the assistance of the lipo device you’ll be able to create common (multi-architecture) information. Normally this device is used for creating common frameworks.
lipo -create -output myFramework.framework gadgets.framework simulator.framework
Think about the next situation: you construct your sources each for arm7 and i386. On an actual machine you’d have to ship the arm7 model, however for the iOS simulator you may want the i386 one. With the assistance of lipo you’ll be able to mix these architectures into one, and ship that framework, so the tip consumer do not have to fret about this subject anymore.
Learn on the article to see the way it’s achieved. 👇
Xcode associated instruments
These instruments could be invoked from the command line as nicely, however they are much extra associated to Xcode than those earlier than. Let’s have a fast walk-through.
xcode-select
Manages the energetic developer listing for Xcode and BSD instruments. You probably have a number of variations of Xcode in your machine this device can simply swap between the developer instruments supplied by the induvidual variations.
xcode-select --switch path/to/Xcode.app
xcrun
Run or find growth instruments and properties. With xcrun you’ll be able to principally run something which you can handle from Xcode.
xcrun simctl checklist #checklist of simulators
codesign
Create and manipulate code signatures
It may signal your utility with the right signature. Normally this factor failed once you have been attempting to signal your app earlier than computerized signing was launched.
codesign -s "Your Firm, Inc." /path/to/MyApp.app
codesign -v /path/to/MyApp.app
xcodebuild
construct Xcode initiatives and workspaces
That is it. It will parse the Xcode challenge or workspace file and executes the suitable buid instructions based mostly on it.
xcodebuild -project Instance.xcodeproj -target Instance
xcodebuild -list
xcodebuild -showsdks
FAT frameworks
Tips on how to make a closed supply common FATtened (multi-architecture) Swift framework for iOS?
So we’re right here, the entire article was made for studying the logic behind this tutorial.
Initially, I do not wish to reinvent the wheel, as a result of there’s a superbly written article that you must learn. Nevertheless, I might like to present you some extra detailed clarification and a little bit modification for the scripts.
Skinny vs. FAT frameworks
Skinny frameworks accommodates compiled code for just one structure. FAT frameworks however are containing “slices” for a number of architectures. Architectures are principally referred as slices, so for instance the i386 or arm7 slice.
This implies, in the event you compile a framework just for i386 and x86_64 architectures, it’ll work solely on the simulator and horribly fail on actual gadgets. So if you wish to construct a very common framework, it’s a must to compile for ALL the prevailing architectures.
Constructing a FAT framework
I’ve a excellent news for you. You simply want one little construct section script and an mixture goal so as to construct a multi-architecture framework. Right here it’s, shamelessly ripped off from the supply article, with some additional modifications… 😁
set -e
BUILD_PATH="${SRCROOT}/construct"
DEPLOYMENT_PATH="${SRCROOT}"
TARGET_NAME="Console-iOS"
FRAMEWORK_NAME="Console"
FRAMEWORK="${FRAMEWORK_NAME}.framework"
FRAMEWORK_PATH="${DEPLOYMENT_PATH}/${FRAMEWORK}"
# clear the construct folder
if [ -d "${BUILD_PATH}" ]; then
rm -rf "${BUILD_PATH}"
fi
# construct the framework for each structure utilizing xcodebuild
xcodebuild -target "${TARGET_NAME}" -configuration Launch
-arch arm64 -arch armv7 -arch armv7s
only_active_arch=no defines_module=sure -sdk "iphoneos"
xcodebuild -target "${TARGET_NAME}" -configuration Launch
-arch x86_64 -arch i386
only_active_arch=no defines_module=sure -sdk "iphonesimulator"
# take away earlier model from the deployment path
if [ -d "${FRAMEWORK_PATH}" ]; then
rm -rf "${FRAMEWORK_PATH}"
fi
# copy freshly constructed model to the deployment path
cp -r "${BUILD_PATH}/Launch-iphoneos/${FRAMEWORK}" "${FRAMEWORK_PATH}"
# merge all of the slices and create the fats framework
lipo -create -output "${FRAMEWORK_PATH}/${FRAMEWORK_NAME}"
"${BUILD_PATH}/Launch-iphoneos/${FRAMEWORK}/${FRAMEWORK_NAME}"
"${BUILD_PATH}/Launch-iphonesimulator/${FRAMEWORK}/${FRAMEWORK_NAME}"
# copy Swift module mappings for the simulator
cp -r "${BUILD_PATH}/Launch-iphonesimulator/${FRAMEWORK}/Modules/${FRAMEWORK_NAME}.swiftmodule/"
"${FRAMEWORK_PATH}/Modules/${FRAMEWORK_NAME}.swiftmodule"
# clear up the construct folder once more
if [ -d "${BUILD_PATH}" ]; then
rm -rf "${BUILD_PATH}"
fi
You may all the time study the created framework with the lipo device.
lipo -info Console.framework/Console
#Architectures within the fats file: Console.framework/Console are: x86_64 i386 armv7 armv7s arm64
Utilization
You simply need to embed your model new framework into the challenge that you just’d like to make use of and set some paths. That is it. Nearly…
Delivery to the App Retailer
There is just one subject with fats architectures. They include slices for the simulator as nicely. If you wish to submit your app to the app retailer, it’s a must to lower off the simulator associated codebase from the framework. The explanation behind that is that no precise actual machine requires this chunk of code, so why submit it, proper?
APP_PATH="${TARGET_BUILD_DIR}/${WRAPPER_NAME}"
# take away unused architectures from embedded frameworks
discover "$APP_PATH" -name '*.framework' -type d | whereas learn -r FRAMEWORK
do
FRAMEWORK_EXECUTABLE_NAME=$(defaults learn "$FRAMEWORK/Data.plist" CFBundleExecutable)
FRAMEWORK_EXECUTABLE_PATH="$FRAMEWORK/$FRAMEWORK_EXECUTABLE_NAME"
echo "Executable is $FRAMEWORK_EXECUTABLE_PATH"
EXTRACTED_ARCHS=()
for ARCH in $ARCHS
do
echo "Extracting $ARCH from $FRAMEWORK_EXECUTABLE_NAME"
lipo -extract "$ARCH" "$FRAMEWORK_EXECUTABLE_PATH" -o "$FRAMEWORK_EXECUTABLE_PATH-$ARCH"
EXTRACTED_ARCHS+=("$FRAMEWORK_EXECUTABLE_PATH-$ARCH")
achieved
echo "Merging extracted architectures: ${ARCHS}"
lipo -o "$FRAMEWORK_EXECUTABLE_PATH-merged" -create "${EXTRACTED_ARCHS[@]}"
rm "${EXTRACTED_ARCHS[@]}"
echo "Changing authentic executable with thinned model"
rm "$FRAMEWORK_EXECUTABLE_PATH"
mv "$FRAMEWORK_EXECUTABLE_PATH-merged" "$FRAMEWORK_EXECUTABLE_PATH"
achieved
This little script will take away all of the pointless slices from the framework, so you can submit your app by way of iTunesConnect, with none points. (ha-ha-ha. 😅)
It’s important to add this final script to your utility’s construct phases.
If you wish to get conversant in the instruments behind the scenes, this text will assist you to with the fundamentals. I could not discover one thing like this however I wished to dig deeper into the subject, so I made one. I hope you loved the article. 😉
