Blit pvrtc texture metal - metal

Question

I'm trying to blit buffer to PVRTC texture. The reason why I'm doing it, because want to keep texture with private storage.
Here is quote from documentation.
If the texture's pixel format is a compressed format, then sourceSize
must be a multiple of the pixel format's block size or be clamped to
the edge of the texture if the block extends outside the bounds of a
texture. For a compressed format, sourceBytesPerRow is the number of
bytes from the start of one row of blocks to the start of the next row
of blocks.
Something wrong in my code, because texture looks broken after.
MTLBlitOption options = MTLBlitOptionNone;
if (_pixelFormat == MTLPixelFormatPVRTC_RGB_4BPP || _pixelFormat == MTLPixelFormatPVRTC_RGBA_4BPP) {
uint32_t blockWidth = 4;
uint32_t blockHeight = 4;
uint32_t bitsPerPixel = 4;
uint32_t blockSize = blockWidth * blockHeight;
uint32_t widthInBlocks = width / blockWidth;
uint32_t heightInBlocks = height / blockHeight;
options = MTLBlitOptionRowLinearPVRTC;
levelBytesPerRow = widthInBlocks * ((blockSize * bitsPerPixel) / 8);
}
id <MTLBuffer> buffer = [device newBufferWithBytes:[data bytes] length:[data length] options:0];
[blitEncoder copyFromBuffer:buffer
sourceOffset:0
sourceBytesPerRow:levelBytesPerRow
sourceBytesPerImage:[buffer length]
sourceSize:MTLSizeMake(width, height, 1)
toTexture:self.textureMetal
destinationSlice:0
destinationLevel:i
destinationOrigin:MTLOriginMake(0, 0, 0)
options:options];