iOS imwrite crash

[zKidor]

System information (version)

• OpenCV => 4.1.2
• Operating System / Platform => iOS 14.1
• Compiler => opencv2.framework download from opencv.org

Detailed description

imread(string) is succ.
but call imwrite(string,mat) crash.

And no crash msg occur.
How can i fix this?
thanks you.

[alalek]

4.1.2

Please try latest release.

crash

If it is crash please provide relevant stacktrace
if it is an exception then use try-catch to dump message.

---

Did you try to write data to your "target" file? (using C/C++ directly: fopen/fwrite orstd::fstream)

[zKidor]

I add try-catch block , but also crash , and could not catch the exception.
I'm sure that the target file is exist in the file system . The target file can be wrote with swiftcode.

[alalek]

Thank you for update!

Perhaps we need to run with OpenCV framework with enabled debug information or built in debug mode to get actual stack trace.
(need to install modern CMake + Xcode command-line tools as prerequisites)

[zKidor]

Hi， @alalek ,
I have install xcode-select and cmake.
How to get actual stack trace?

[alalek]

Check:

• iOS tutorials
• CI logs

---

How to get actual stack trace?

Build new framework using the instructions above (with debug information)
Update your project with new framework (dump cv::getBuildInformation() to ensure that it is updated)
Hopefully Xcode would show more relevant data.

[zKidor]

Hi @alalek
I have rebuild the opencv framework 4.5 with opencv contrib.

python opencv/platforms/ios/build_framework.py ios --contrib opencv_contrib

But it also crash with imwrite(String,mat) on iOS 14.
And there is no crash msg or stack

I also modify the build_framework.py in platform/ios/

and crash in
jpeg_create_compress

Can it help?

I take the same input image (.png) , on Android , call imwrite(string,mat) , it can be done . on iOS , it crash.

[zKidor]

Hi @alalek ,
Is there any update for my issue ?

[hellodoge]

Hello, @alalek

3rdparty/libjpeg-turbo/src/jpeglib.h:

* NB: you must set up the error-manager BEFORE calling jpeg_create_xxx.

Consider moving the jpeg_create_compress line two lines down.