Merge pull request #17165 from komakai:objc-binding

Objc binding

* Initial work on Objective-C wrapper

* Objective-C generator script; update manually generated wrappers

* Add Mat tests

* Core Tests

* Imgproc wrapper generation and tests

* Fixes for Imgcodecs wrapper

* Miscellaneous fixes. Swift build support

* Objective-C wrapper build/install

* Add Swift wrappers for videoio/objdetect/feature2d

* Framework build;iOS support

* Fix toArray functions;Use enum types whenever possible

* Use enum types where possible;prepare test build

* Update test

* Add test runner scripts for iOS and macOS

* Add test scripts and samples

* Build fixes

* Fix build (cmake 3.17.x compatibility)

* Fix warnings

* Fix enum name conflicting handling

* Add support for document generation with Jazzy

* Swift/Native fast accessor functions

* Add Objective-C wrapper for calib3d, dnn, ml, photo and video modules

* Remove IntOut/FloatOut/DoubleOut classes

* Fix iOS default test platform value

* Fix samples

* Revert default framework name to opencv2

* Add converter util functions

* Fix failing test

* Fix whitespace

* Add handling for deprecated methods;fix warnings;define __OPENCV_BUILD

* Suppress cmake warnings

* Reduce severity of "jazzy not found" log message

* Fix incorrect #include of compatibility header in ios.h

* Use explicit returns in subscript/get implementation

* Reduce minimum required cmake version to 3.15 for Objective-C/Swift binding

CMakeLists.txt

@@ -452,6 +452,7 @@ OCV_OPTION(BUILD_FAT_JAVA_LIB       "Create Java wrapper exporting all functions
 OCV_OPTION(BUILD_ANDROID_SERVICE    "Build OpenCV Manager for Google Play" OFF IF ANDROID )
 OCV_OPTION(BUILD_CUDA_STUBS         "Build CUDA modules stubs when no CUDA SDK" OFF  IF (NOT APPLE_FRAMEWORK) )
 OCV_OPTION(BUILD_JAVA               "Enable Java support"                         (ANDROID OR NOT CMAKE_CROSSCOMPILING)  IF (ANDROID OR (NOT APPLE_FRAMEWORK AND NOT WINRT)) )
+OCV_OPTION(BUILD_OBJC               "Enable Objective-C support"                  ON  IF APPLE_FRAMEWORK )
 
 # OpenCV installation options
 # ===================================================
@@ -1595,6 +1596,12 @@ if(BUILD_JAVA)
   status("    Java tests:"    BUILD_TESTS AND opencv_test_java_BINARY_DIR                                 THEN YES ELSE NO)
 endif()
 
+# ========================== Objective-C =======================
+if(BUILD_OBJC)
+  status("")
+  status("  Objective-C wrappers:" HAVE_opencv_objc                                                       THEN YES ELSE NO)
+endif()
+
 ocv_cmake_hook(STATUS_DUMP_EXTRA)
 
 # ========================== auxiliary ==========================