Add helpers to create errors in ObjC/Swift

Author: shoumikhin

extension/apple/ExecuTorch/Exported/ExecuTorchError.h

@@ -12,4 +12,62 @@ NS_ASSUME_NONNULL_BEGIN
 
 FOUNDATION_EXPORT NSErrorDomain const ExecuTorchErrorDomain NS_SWIFT_NAME(ErrorDomain);
 
+/**
+ * Enum to define the error codes.
+ * Values can be a subset, but must numerically match exactly those defined in
+ * runtime/core/error.h
+ */
+typedef NS_ERROR_ENUM(ExecuTorchErrorDomain, ExecuTorchErrorCode) {
+  // System errors.
+  ExecuTorchErrorCodeOk                             = 0,
+  ExecuTorchErrorCodeInternal                       = 1,
+  ExecuTorchErrorCodeInvalidState                   = 2,
+  ExecuTorchErrorCodeEndOfMethod                    = 3,
+
+  // Logical errors.
+  ExecuTorchErrorCodeNotSupported                   = 16,
+  ExecuTorchErrorCodeNotImplemented                 = 17,
+  ExecuTorchErrorCodeInvalidArgument                = 18,
+  ExecuTorchErrorCodeInvalidType                    = 19,
+  ExecuTorchErrorCodeOperatorMissing                = 20,
+
+  // Resource errors.
+  ExecuTorchErrorCodeNotFound                       = 32,
+  ExecuTorchErrorCodeMemoryAllocationFailed         = 33,
+  ExecuTorchErrorCodeAccessFailed                   = 34,
+  ExecuTorchErrorCodeInvalidProgram                 = 35,
+  ExecuTorchErrorCodeInvalidExternalData            = 36,
+  ExecuTorchErrorCodeOutOfResources                 = 37,
+
+  // Delegate errors.
+  ExecuTorchErrorCodeDelegateInvalidCompatibility   = 48,
+  ExecuTorchErrorCodeDelegateMemoryAllocationFailed = 49,
+  ExecuTorchErrorCodeDelegateInvalidHandle          = 50,
+} NS_SWIFT_NAME(ErrorCode);
+
+/**
+ * Returns a brief error description for the given error code.
+ *
+ * @param code An ExecuTorchErrorCode value representing the error code.
+ * @return An NSString containing the error description.
+ */
+FOUNDATION_EXPORT
+__attribute__((deprecated("This API is experimental.")))
+NSString *ExecuTorchErrorDescription(ExecuTorchErrorCode code)
+    NS_SWIFT_NAME(ErrorDescription(_:));
+
+/**
+ * NSError convenience initializer for ExecuTorch errors.
+ *
+ * @param code The ExecuTorchErrorCode to wrap into an NSError.
+ * @return An NSError with ExecuTorchErrorDomain, the specified code, and a localized description.
+ */
+ @interface NSError (ExecuTorch)
+
+ + (instancetype)errorWithExecuTorchCode:(ExecuTorchErrorCode)code
+     __attribute__((deprecated("This API is experimental.")))
+     NS_SWIFT_NAME(init(code:));
+
+@end
+
 NS_ASSUME_NONNULL_END