MPSImageIntegral returning all zeros - macos

Question

I am trying to use MPSImageIntegral to calculate the sum of some elements in an MTLTexture. This is what I'm doing:
std::vector<float> integralSumData;
for(int i = 0; i < 10; i++)
integralSumData.push_back((float)i);
MTLTextureDescriptor *textureDescriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatR32Float
width:(integralSumData.size()) height:1 mipmapped:NO];
textureDescriptor.usage = MTLTextureUsageShaderRead | MTLTextureUsageShaderWrite;
id<MTLTexture> texture = [_device newTextureWithDescriptor:textureDescriptor];
// Calculate the number of bytes per row in the image.
NSUInteger bytesPerRow = integralSumData.size() * sizeof(float);
MTLRegion region =
{
{ 0, 0, 0 }, // MTLOrigin
{integralSumData.size(), 1, 1} // MTLSize
};
// Copy the bytes from the data object into the texture
[texture replaceRegion:region
mipmapLevel:0
withBytes:integralSumData.data()
bytesPerRow:bytesPerRow];
MTLTextureDescriptor *textureDescriptor2 = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatR32Float
width:(integralSumData.size()) height:1 mipmapped:NO];
textureDescriptor2.usage = MTLTextureUsageShaderRead | MTLTextureUsageShaderWrite;
id<MTLTexture> outtexture = [_device newTextureWithDescriptor:textureDescriptor2];
// Create a MPS filter.
MPSImageIntegral *integral = [[MPSImageIntegral alloc] initWithDevice: _device];
MPSOffset offset = { 0,0,0};
[integral setOffset:offset];
[integral setEdgeMode:MPSImageEdgeModeZero];
[integral encodeToCommandBuffer:commandBuffer sourceTexture:texture destinationTexture:outtexture];
[commandBuffer commit];
[commandBuffer waitUntilCompleted];
But, when I check my outtexture values, its all zeroes. Am I doing something wrong? Is this a correct way in which I shall use MPSImageIntegral?
I'm using the following code to read values written into the outTexture:
float outData[100];
[outtexture getBytes:outData bytesPerRow:bytesPerRow fromRegion:region mipmapLevel:0];
for(int i = 0; i < 100; i++)
std::cout << outData[i] << "\n";
Thanks

Answer 1

As pointed out by #Matthijis: All I had to do was use an MTLBlitEncoder to make sure I synchronise my MTLTexture before reading it into CPU, and it worked like charm!