Tensor constructor to create with an existing NSData.

Summary: #8366

Reviewed By: mergennachin

Differential Revision: D71929159

Author: shoumikhin

extension/apple/ExecuTorch/Exported/ExecuTorchTensor.h

@@ -345,4 +345,28 @@ __attribute__((deprecated("This API is experimental.")))
 
 @end
 
+#pragma mark - Data Category
+
+@interface ExecuTorchTensor (Data)
+
+/**
+ * Initializes a tensor using an NSData object as the underlying data buffer.
+ *
+ * @param data An NSData object containing the tensor data.
+ * @param shape An NSArray of NSNumber objects representing the tensor's shape.
+ * @param strides An NSArray of NSNumber objects representing the tensor's strides.
+ * @param dimensionOrder An NSArray of NSNumber objects indicating the order of dimensions.
+ * @param dataType An ExecuTorchDataType value specifying the element type.
+ * @param shapeDynamism An ExecuTorchShapeDynamism value indicating the shape dynamism.
+ * @return An initialized ExecuTorchTensor instance using the provided data.
+ */
+- (instancetype)initWithData:(NSData *)data
+                       shape:(NSArray<NSNumber *> *)shape
+                     strides:(NSArray<NSNumber *> *)strides
+              dimensionOrder:(NSArray<NSNumber *> *)dimensionOrder
+                    dataType:(ExecuTorchDataType)dataType
+               shapeDynamism:(ExecuTorchShapeDynamism)shapeDynamism;
+
+@end
+
 NS_ASSUME_NONNULL_END

extension/apple/ExecuTorch/Exported/ExecuTorchTensor.mm

@@ -31,6 +31,7 @@ NSInteger ExecuTorchElementCountOfShape(NSArray<NSNumber *> *shape) {
 
 @implementation ExecuTorchTensor {
   TensorPtr _tensor;
+  NSData *_data;
   NSArray<NSNumber *> *_shape;
   NSArray<NSNumber *> *_strides;
   NSArray<NSNumber *> *_dimensionOrder;
@@ -274,3 +275,27 @@ - (instancetype)initWithBytes:(const void *)pointer
 }
 
 @end
+
+@implementation ExecuTorchTensor (Data)
+
+- (instancetype)initWithData:(NSData *)data
+                       shape:(NSArray<NSNumber *> *)shape
+                     strides:(NSArray<NSNumber *> *)strides
+              dimensionOrder:(NSArray<NSNumber *> *)dimensionOrder
+                    dataType:(ExecuTorchDataType)dataType
+               shapeDynamism:(ExecuTorchShapeDynamism)shapeDynamism {
+  ET_CHECK_MSG(data.length >= ExecuTorchElementCountOfShape(shape) * ExecuTorchSizeOfDataType(dataType),
+               "Data length is too small");
+  self = [self initWithBytesNoCopy:(void *)data.bytes
+                             shape:shape
+                           strides:strides
+                    dimensionOrder:dimensionOrder
+                          dataType:dataType
+                     shapeDynamism:shapeDynamism];
+  if (self) {
+    _data = data;
+  }
+  return self;
+}
+
+@end

extension/apple/ExecuTorch/__tests__/TensorTest.swift

@@ -101,6 +101,16 @@ class TensorTest: XCTestCase {
     }
   }
 
+  func testInitData() {
+    let dataArray: [Float] = [1.0, 2.0, 3.0, 4.0]
+    let data = Data(bytes: dataArray, count: dataArray.count * MemoryLayout<Float>.size)
+    let tensor = Tensor(data: data, shape: [4], strides: [1], dimensionOrder: [0], dataType: .float, shapeDynamism: .static)
+    XCTAssertEqual(tensor.count, 4)
+    tensor.bytes { pointer, count, dataType in
+      XCTAssertEqual(Array(UnsafeBufferPointer(start: pointer.assumingMemoryBound(to: Float.self), count: count)), dataArray)
+    }
+  }
+
   func testWithCustomStridesAndDimensionOrder() {
     let data: [Float] = [1.0, 2.0, 3.0, 4.0]
     let tensor = Tensor(