When I tried to compile my XCode project with OpenCV 2.4 iOS using XCode 7 + iOS SDK 9, XCode complained that
ld:
'opencv2.framework/opencv2(alloc.o)'
does not contain bitcode. You must rebuild it with bitcode enabled
(Xcode setting ENABLE_BITCODE), obtain an updated library from the
vendor, or disable bitcode for this target. for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
and refused to link. After some googling, it turns out to be because Apple added a new feature named Bitcode for app optimization within App Store. While OpenCV iOS binary hasn't been updated to include Bitcode, it cannot pass the link stage.
Some reference pointed out a temporary solution to disable ENABLE_BITCODE so the linking could be done without Bitcode. This will prevent the app being compiled for Apple Watches because Bitcode is mandatory for Watch Apps. Therefore my question is, are there some (best easy) ways to compile iOS OpenCV with Bitcode enabled? (better with a download link for compiled framework)
After some search and trial, I figured out a way to compile OpenCV iOS from the source with Bitcode. A compiled binary is also provided here: [v3.0] [v2.4]. [Disclaimer: I am not responsible for the integrity of the compiled binary. Use at your own risk.]
The steps of compilation is basically the same as the official document, with only one extra step.
Download the code with git:
cd ~/<my_working_directory>
git clone https://github.com/Itseez/opencv.git
Make symbolic link for Xcode to let OpenCV build scripts find the compiler, header files etc.
cd /
sudo ln -s /Applications/Xcode.app/Contents/Developer Developer
[Key Step] Change the compilation script to add the extra option for Bitcode: edit ~/<my_working_directory>/opencv/platform/ios/build_framework.py, and locate the line containing -DCMAKE_C_FLAGS. Add a flag of -fembed-bitcode. For example, in the source I got, it's line 55, and will look like
"-DCMAKE_C_FLAGS=\"-Wno-implicit-function-declaration -fembed-bitcode\" " +
after the change. [ref]
Build OpenCV framework:
cd ~/<my_working_directory>
python opencv/platforms/ios/build_framework.py ios
If everything’s fine, a few minutes later you will get ~/<my_working_directory>/ios/opencv2.framework. You can add this framework to your Xcode projects.
P.S. Ask a question, even when you already know the answer is encouraged according to this post on Meta Stackchange.
OpenCV is precisely the kind of software (along with audio and video Codecs) that is likely to have hand-rolled ARM NEON optimisations. The documentation suggests that ~40 functions have had this treatment in OpenCV3.0.
If compiling for LLVM bit-code you'll get the generic (less optimised, implemented in C or C++) versions instead.
Use of Bitcode is optional - except when compiling for Apple watch, where it's hard to imagine you'd run computationally complex image processing anyway. If you're bundling a watch app, override the build setting for bitcode on it only.
Related
I have to support OpenSSL in my project in building my iPad app for UIKitForMac. Currently, I get these errors.
Building for UIKit for Mac, but the linked library 'libssl.a' was built for freestanding. You may need to restrict the platforms for which this library should be linked in the target editor.
Building for UIKit for Mac, but the linked library 'libcrypto.a' was built for freestanding. You may need to restrict the platforms for which this library should be linked in the target editor.
I was reading about XCFrameworks, but Apple really hasn't put out much information here. Has anyone figured out build scenarios?
The solution in the comments doesn't work for me. However, I just build to different libs: iOS as I used to and another one for Catalyst by adding the build parameters: -target x86_64-apple-ios13.0-macabi and defining Mac SDK in -isysroot. After that, I just conditionally add each of the libraries for each build version and it works.
Amid mounting frustration following many failed attempts and Google searches, I successfully built openSSL 1.1.1g for Catalyst, compiled my project, linked openSSL and launched the app on my Mac by doing the following:
I used the same directory in to which I had previously extracted and built openSSL for IOS.
Following instructions here, I edited <openSSL directory>/Configurations/10-main.conf. Scrolling down to the "darwin64-x86_64-cc" section, I added a second CFLAGS line:
CFLAGS => add("-target x86_64-apple-ios13.0-macabi"),
In the openSSL directory, execute ./Configure darwin64-x86_64-cc -shared Note that I've seen several other versions of this Configure statement, some with many more options. This command worked for me, but I'm not sure what all the other variations do. You may want to research this further.
Execute make clean to clear all the objects from the prior IOS build
Execute make This successfully built openSSL.
In Xcode, under -> General -> "Frameworks, Libraries and Embedded Content" I removed both libcrypto.a and libssl.a this was a critical step
Switching tabs to Build Phases -> Link Binary With Libraries, verify both archives are removed from this section as well. (It appeared that removing them in step 5 also cleared them in step 6, but I'm not certain).
Back on General -> Frameworks, click the + to add new entries, select "add other" in the lower left corner of the popup window, then provide the path to the newly built libcrypto.a. Repeat for libssl.a
Delete the derived data in a terminal window (I'm not certain this was necessary, but did it out of an abundance of caution):
cd ~/Library/Developer/Xcode
mv DerivedData DerivedData.old
Build the project in Xcode. This successfully completed.
Steps 5-7 turned out to be critical. Even though I moved and/or completely replaced the prior libraries, when I tried to build in Xcode I would get linker errors that I was building for MacOS Catalina but trying to link something built for MacOS x86.
I'm trying to import Firebase into my iOS app. I followed this tutorial for doing this manually with Objective-C (as opposed to using CocoaPods).
http://www.mokacoding.com/blog/setting-up-firebase-without-cocoapods/
When I try to build my project, I get the following errors:
"Apple Mach-O Linker Error"
"Linker command failed with exit code 1 (use -v to see invocation)"
I'm familiar with the Linux CLI (less so with Macs), but I don't understand how to apply the -v flag to XCode's build process to get more info.
I've been Googling this for the last 3 hours, but every answer I find seems to be directed at users who weren't using an XCode workspace with CocoaPods.
I don't have CocoaPods installed, so I don't think this is my issue. Despite that I have converted my project and properly imported it into an XCode workspace, this still didn't solve my problem.
My app is a Swift project, and I have imported the modulemap, firebase.h, and googleServices.plist files.
I've also made my Header and Library search paths recursive for the entire project folder in an attempt to fix this.
Here's my project navigation. Although at this point I suspect it's some kind of build setting that isn't correct.
Some selected answers I've tried to apply without success:
Apple Mach -O Linker command failed
In Xcode how do I create a new workspace and add 1 project to it so that I can see the project and its files?
Framework not found GoogleToolboxForMac
Adding system header search path to Xcode
https://github.com/firebase/firebase-ios-sdk/issues/258
Apple Mach-O Linker & Ditto Error - Xcode 8
https://github.com/invertase/react-native-firebase/issues/198
https://forum.ionicframework.com/t/ios-xcode-8-apple-mach-o-linker-ld-error-group-in-xcode/89903
Upgrading to xcode 9.2 fixes this. It appears to be an issue with earlier versions not properly handling linking.
Which is misleading b/c the firebase documentation indicates it's compatible with xcode 8. But I think that's assuming you use cocoapods. If you don't, and instead try to link the obj-c frameworks you need xcode 9+
Once I knew how to examine the more verbose linking error, googling for x86_64 led me to some helpful answers.
This and other answers helped me investigate upgrading.
ld: framework not found Stripe for architecture x86_64
How can I compile WebRTC iOS framework with Bitcode enabled. Currently I have to disable the Bitcode of my project due to WebRTC framework.
You will need to build it yourself.
Something like:
# Clone the depot tools
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
# Add the tools to the path
export PATH=$PATH:"`pwd`/depot_tools"
# Download the WebRTC source code
mkdir webrtc_ios
cd webrtc_ios
# This will take some time
fetch --nohooks webrtc_ios
gclient sync
# Let's start building
cd src
# Build the framework, remove --arch "arm64 x64" to build ALL architectures, including 32 bit
tools_webrtc/ios/build_ios_libs.py --bitcode --arch arm64 x64
# The framework is at out_ios_libs/WebRTC.framework
Documentation: https://webrtc.github.io/webrtc-org/native-code/ios/
Update:
Starting with Xcode 14, bitcode is no longer required (see release notes), and no longer supported in submissions.
The google WebRTC neglected to fix an ARM build issue with bitcode for so long, they just waited it out...
the --bitcode option is no longer supported by the build script.
To continue building using my instructions, remove it:
tools_webrtc/ios/build_ios_libs.py --arch arm64 x64
according to the official doc, you have to compile manually. More details there:
main page: https://webrtc.org/native-code/development/
iOS page: https://webrtc.org/native-code/ios/
bottom of the page (last paragraph) includes instructions to build with bitcode support:
To build the framework with bitcode support, pass the --bitcode flag to the script like so
python build_ios_libs.py --bitcode
The README claims it can compile to armv7, but I cannot find the magic incantation to make it work.
I started down the rabbit hole of changing the Makefile to set the arch=armv7, fixing the resulting compilation errors, etc, but that doesn't seem like the right way to go about it.
There recommended cmake flags are:
cmake -DLLVM_TARGETS_TO_BUILD="X86;ARM;NVPTX" -DLLVM_ENABLE_ASSERTIONS=ON -DCMAKE_BUILD_TYPE=Release ..
But alas, the bin directory contains only a .a and a .so, both of which are compiled for x86_64. There are no dylibs.
I can successfully run the test iOS app in the simulator, linking with the x86 libraries, but I cannot build on a device since there are no arm binaries.
Here is a link to the Halide test app I'm trying to build:
https://github.com/halide/Halide/tree/master/apps/HelloiOS
You should use AOT compilation for iOS. The JIT in principle works on ARM (the architecture), but not on iOS (the OS).
Clarification: are you trying to build Halide to run on ARM, or merely to generate code for ARM? (If the latter, any target will do, as all builds of Halide can generate code for all known targets.)
My project was working just fine until this morning. I was using xcode 4.3, and an older version of OpenCV (I'm not sure about the exact version). OSX was already 10.7.x, but not 10.7.5
Today, after upgrading OSX to 10.7.5, xcode to 4.5.2, and downloading OpenCV 2.4.3, I am getting the following linker errors when trying to build the project:
Undefined symbols for architecture armv7:
"_OBJC_CLASS_$_ALAssetsLibrary", referenced from:
objc-class-ref in opencv2(cap_ios_video_camera.o)
"cv::FeatureDetector::create(std::string const&)", referenced from:
-[ImageAnalyzer detectBlobs:] in ImageAnalyzer.o
"cv::FeatureDetector::detect(cv::Mat const&, std::vector >&, cv::Mat const&) const", referenced from:
-[ImageAnalyzer detectBlobs:] in ImageAnalyzer.o
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)
In order to use the new opencv framework I removed the reference to the old framework, and referenced the project to the official prebuilt opencv2.framework downloaded from here.
I also removed the reference to libz.dylib, and added a reference to libc++.dylib instead.
Last step was to update the prefix file to the new framework. The relevant part in the prefix file now looks like this:
#ifdef __cplusplus
#import <opencv2/opencv.hpp>
#endif
It all narrowed down to these 4 linker errors I can't seem to get rid of. I tried using libstdc++.dylib, but I am getting even more errors. I also tried building OpenCV myself as explained here, but I am still getting the same errors as the prebuilt framework.
What did I miss? Is there anything else I need to change in my project?
UPDATE:
As seen here, setting the "C++ Standard Library" to "libc++ (LLVM C++ standard libray with C++ 11 support" yielded only one error:
clang: error: invalid deployment target for -stdlib=libc++ (requires iOS 5.0 or later)
Changing the deployment target to iOS 5 finally got my project to run again.
Does this mean OpenCV 2.4.3 doesn't work on iOS versions older than 5?
steps to compile and run c++ opencv 2.4.4 on mac os x lion 10.7.5 with cmake 2.8.10 and xcode 4.6.1
Having the right tools
download opencv-unix from http://sourceforge.net/projects/opencvlibrary/files/ and untar it wherever
download cmake .dmg from http://www.cmake.org/cmake/resources/software.html and install it
i am assuming you have xcode 4.6 on os x lion which includes the ios sdk 6.1
go to xcode preferences to download and install the Command Line Tools so you have g++ etc.
Use cmake to compile opencv
go to the extracted opencv folder
create a build directory
mkdir build
cd build
cmake -D WITH_TBB=OFF -D BUILD_NEW_PYTHON_SUPPORT=OFF -D BUILD_FAT_JAVA_LIB=OFF -D BUILD_TBB=OFF -D BUILD_EXAMPLES=ON -D CMAKE_CXX_COMPILER=g++ CMAKE_CC_COMPILER=gcc -D CMAKE_OSX_ARCHITECTURES=x86_64 -D BUILD_opencv_java=OFF -G "Unix Makefiles" ..
make -j8
sudo make install
from the build folder, go to bin/ and run one of the tests
./opencv_test_stitching
Create your own c++ opencv xcode project
fire up xcode and create a new xcode project
select Command Line Tool for the type of project under os x
open your project's build settings
under Architectures, set Architecture to 64-bit intel. also set Valid Architectures to x86_64
under Build Options, set Compiler for C/C++ to Default Compiler
under Search Paths, set Header Search Paths to /usr/local/include
also under Search Paths, set Library Search Paths to /usr/local/lib
under Apple LLVM compiler 4.2 - Language set C++ Standard Library to libstd++ (For OpenCV 2.4.6, Xcode 5, LLVM 5.0, and 10.8.5, set both language dialect and std library to "Compiler Default" instead of "libstd++")
Add the compiled opencv libraries to your project
go the the Build Phases tab next to Build Settings tab you were in
inside Link Binary With Libraries, click on the + sign and choose Add Other
hit the front slash / on your keyboard and enter /usr/local/lib
hit enter and select the libraries you want to use in your project
make sure you always select libopencv_core.2.4.4.dylib
hit enter and you will see the selected dylibs under your project
write some code
first lets organize the files, right click on your project blueprint icon and select New Group
name the new group opencv or whatever
drag the dylibs and drop them in that group
open main.cpp
copy code from any of the sample tests that came with opencv and paste it here
make sure all the required dylibs are added, for example, if you copied the opencv_test_stitching.cpp code into main.cpp, you will need to add the following libraries in the previous steps
libopencv_core.2.4.4.dylib
libopencv_highgui.2.4.4.dylib
libopencv_stitching.2.4.4.dylib
Cheers.
It seems that your project is missing the framework AssetsLibrary.
Select the top node in the project navigator. (The project and targets page with the build settings appears.)
Select the target.
Select Summary.
Scroll down to Linked Frameworks and Libraries.
Click the Plus icon at the end of the table and select AssetsLibrary.framework.
Click Add.
Then try to build it again.
Since I can't seem to get an answer regarding the versions (neither here nor at the OpenCV Q&A site), I'm going to post this as an answer, as it at least solved the issue. This is described here.
In your project's Build Settings, go down to the section Apple LLVM compiler 4.1-Language.
There:
Set C++ Language Dialect to Compiler Default
Set C++ Standard Libray to libc++ (LLVM C++ standard libray with C++ 11 support
After doing the above, I stopped getting those linker errors, and only got one error instead, which stated that only iOS 5 and above is supported. Changing the Deployment Target to 5.0 in the project summery did the trick.
On a final note, I'm still not sure what it means, regarding OpenCV 2.4.3's compatibility with iOS versions older than 5.
clang: error: invalid deployment target for -stdlib=libc++ (requires iOS 5.0 or later) to remove this error.
GoTo BuildSettings. Set c++ standard library to compiler default. The
error will get removed surely.
Just to get this into the postings somewhere in case someone else runs into the same thing. If you follow all the great advice aboutsetting the proper c++ library to link against for building an iOS app BUT still get the link errors for undefined symbols make sure your code files are set to compile as c++! That is rename your .m to .mm and .h to .hpp. It's the little things...
Instead of using terminal commands given in the opencv installation guide in official website, use the following commands to build opencv from terminal. Worked for me.
cd OpenCV-2.3.1
mkdir build
cd build
cmake -G "Unix Makefiles" ..
make
sudo make install
Go Xcode/General/Linked Frameworks and Libraries
Press "+" button
type: AssetsLibrary
Select "AssetsLibrary.framework" and import it
Done
Good luck!