Add copy API to ExecuTorchValue (pytorch#10954)

Author: bsoyluoglu

extension/apple/ExecuTorch/Exported/ExecuTorchValue.h

@@ -50,7 +50,7 @@ typedef float ExecuTorchFloatValue
  */
 NS_SWIFT_NAME(Value)
 __attribute__((deprecated("This API is experimental.")))
-@interface ExecuTorchValue : NSObject
+@interface ExecuTorchValue : NSObject <NSCopying>
 
 /**
  * The tag that indicates the dynamic type of the value.
@@ -208,6 +208,12 @@ __attribute__((deprecated("This API is experimental.")))
 + (instancetype)valueWithDouble:(ExecuTorchDoubleValue)value
     NS_SWIFT_NAME(init(_:));
 
+/**
+ * Returns a copy of the value.
+ *
+ * @return A new ExecuTorchValue instance that is a duplicate of the current value.
+ */
+ - (instancetype)copy;
 
 /**
  * Determines whether the current Value is equal to another Value.

extension/apple/ExecuTorch/Exported/ExecuTorchValue.mm

@@ -57,6 +57,15 @@ - (instancetype)initWithTag:(ExecuTorchValueTag)tag
   return self;
 }
 
+- (instancetype)copy {
+  return [self copyWithZone:nil];
+}
+
+- (instancetype)copyWithZone:(nullable NSZone *)zone {
+  return [[ExecuTorchValue allocWithZone:zone] initWithTag:_tag
+                                                     value:[_value copyWithZone:zone]];
+}
+
 - (ExecuTorchValueTag)tag {
   return _tag;
 }