Add data pointer bridge method to Mat for Objective-C/Swift

modules/core/misc/objc/common/Mat.h

@@ -97,6 +97,7 @@ CV_EXPORTS @interface Mat : NSObject
 - (void)createEx:(NSArray<NSNumber*>*)sizes type:(int)type  NS_SWIFT_NAME(create(sizes:type:));
 - (void)copySize:(Mat*)mat;
 - (Mat*)cross:(Mat*)mat;
+- (unsigned char*)dataPtr NS_SWIFT_NAME(dataPointer());
 - (int)depth;
 - (Mat*)diag:(int)diagonal;
 - (Mat*)diag;

modules/core/misc/objc/common/Mat.mm

@@ -286,6 +286,10 @@ static bool updateIdx(cv::Mat* mat, std::vector<int>& indices, int inc) {
     return [[Mat alloc] initWithNativeMat:new cv::Mat(_nativePtr->cross(*(cv::Mat*)mat.nativePtr))];
 }
 
+- (unsigned char*)dataPtr {
+    return _nativePtr->data;
+}
+
 - (int)depth {
     return _nativePtr->depth();
 }