Repository: opencv
Issue: Objective-C++ files importing Objective-C bindings fail to build when using a `framework_name` other than `opencv2`
Labels: bug,category: build/install,platform: ios/osx,category: swift/objc bindings

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##### System information (version)
<!-- Example
- OpenCV => 4.2
- Operating System / Platform => Windows 64 Bit
- Compiler => Visual Studio 2017
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- OpenCV => 4.5.5
- Operating System / Platform => iOS 15.4
- Compiler => Xcode 13.3

##### Detailed description

When the OpenCV framework is built using a non-default framework name, importing the Objective-C umbrella header into an Objective-C++ file results in a build failure, as apparently opencv2 is hard-coded in one of the include paths.

##### Steps to reproduce

1. Build an iOS framework: `python3 opencv-source/platforms/apple/build_xcframework.py --out staging --iphoneos_archs arm64 --build_only_specified_archs --framework_name OpenCV
2. Add it to an Objective-C project
3. Import <OpenCV/OpenCV.h> into an Objective-C++ file (.mm)
4. Observe the build failure
```
OpenCV.framework/Headers/Mat.h:10:9: 'opencv2/core.hpp' file not found
OpenCVFrameworkName/OpenCVFrameworkName/ViewController.mm:9:9: in file included from OpenCVFrameworkName/OpenCVFrameworkName/ViewController.mm:9:
OpenCV.framework/Headers/OpenCV.h:9:9: in file included from OpenCV.framework/Headers/OpenCV.h:9:
OpenCV.framework/Headers/MatOfRect2d.h:9:9: in file included from OpenCV.framework/Headers/MatOfRect2d.h:9:
```

Mat.h starts with
```c++
#ifdef __cplusplus
#import "opencv2/core.hpp"
#else
#define CV_EXPORTS
#endif
```

Which is hard-coded to `opencv2` even when the framework name is `OpenCV`.

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