Add Tensor resizing API.

extension/apple/ExecuTorch/Exported/ExecuTorchTensor.h

@@ -189,6 +189,17 @@ __attribute__((deprecated("This API is experimental.")))
 - (void)mutableBytesWithHandler:(void (^)(void *pointer, NSInteger count, ExecuTorchDataType dataType))handler
     NS_SWIFT_NAME(mutableBytes(_:));
 
+/**
+ * Resizes the tensor to a new shape.
+ *
+ * @param shape An NSArray of NSNumber objects representing the desired new shape.
+ * @param error A pointer to an NSError pointer that is set if an error occurs.
+ * @return YES if the tensor was successfully resized; otherwise, NO.
+ */
+- (BOOL)resizeToShape:(NSArray<NSNumber *> *)shape
+                error:(NSError **)error
+    NS_SWIFT_NAME(resize(to:));
+
 + (instancetype)new NS_UNAVAILABLE;
 - (instancetype)init NS_UNAVAILABLE;
 

extension/apple/ExecuTorch/Exported/ExecuTorchTensor.mm

@@ -15,6 +15,7 @@
 
 using namespace executorch::aten;
 using namespace executorch::extension;
+using namespace executorch::runtime;
 
 NSInteger ExecuTorchSizeOfDataType(ExecuTorchDataType dataType) {
   return elementSize(static_cast<ScalarType>(dataType));
@@ -108,6 +109,25 @@ - (void)mutableBytesWithHandler:(void (^)(void *pointer, NSInteger count, ExecuT
   handler(_tensor->unsafeGetTensorImpl()->mutable_data(), self.count, self.dataType);
 }
 
+- (BOOL)resizeToShape:(NSArray<NSNumber *> *)shape
+                error:(NSError **)error {
+  const auto resizeError = resize_tensor_ptr(
+    _tensor, utils::toVector<SizesType>(shape)
+  );
+  if (resizeError != Error::Ok) {
+    if (error) {
+      *error = [NSError errorWithDomain:ExecuTorchErrorDomain
+                                   code:(NSInteger)resizeError
+                               userInfo:nil];
+    }
+    return NO;
+  }
+  _shape = nil;
+  _strides = nil;
+  _dimensionOrder = nil;
+  return YES;
+}
+
 @end
 
 @implementation ExecuTorchTensor (BytesNoCopy)

extension/apple/ExecuTorch/__tests__/TensorTest.swift

@@ -165,4 +165,29 @@ class TensorTest: XCTestCase {
     XCTAssertEqual(tensor1.dimensionOrder, tensor2.dimensionOrder)
     XCTAssertEqual(tensor1.count, tensor2.count)
   }
+
+  func testResize() {
+    var data: [Int] = [1, 2, 3, 4]
+    let tensor = data.withUnsafeMutableBytes {
+      Tensor(bytesNoCopy: $0.baseAddress!, shape: [4, 1], dataType: .int)
+    }
+    XCTAssertNoThrow(try tensor.resize(to: [2, 2]))
+    XCTAssertEqual(tensor.dataType, .int)
+    XCTAssertEqual(tensor.shape, [2, 2])
+    XCTAssertEqual(tensor.strides, [2, 1])
+    XCTAssertEqual(tensor.dimensionOrder, [0, 1])
+    XCTAssertEqual(tensor.count, 4)
+
+    tensor.bytes { pointer, count, dataType in
+      XCTAssertEqual(Array(UnsafeBufferPointer(start: pointer.assumingMemoryBound(to: Int.self), count: count)), data)
+    }
+  }
+
+  func testResizeError() {
+    var data: [Int] = [1, 2, 3, 4]
+    let tensor = data.withUnsafeMutableBytes {
+      Tensor(bytesNoCopy: $0.baseAddress!, shape: [4, 1], dataType: .int)
+    }
+    XCTAssertThrowsError(try tensor.resize(to: [2, 3]))
+  }
 }