src/Leevel/Http/Response.php
public function setLastModified(DateTime $datetime = null): IResponse
    {
        if ($this->checkFlowControl()) {
            return $this;
        }

        if (null === $datetime) {
            $this->headers->remove('Last-Modified');

            return $this;
        }

        $this->setHeader('Last-Modified', $this->normalizeDateTime($datetime));

        return $this;
    }
public function setLastModified(DateTime $datetime = null): IResponse
    {
        if ($this->checkFlowControl()) {
            return $this;
        }

        if (null === $datetime) {
            $this->headers->remove('Last-Modified');

            return $this;
        }

        $this->setHeader('Last-Modified', $this->normalizeDateTime($datetime));

        return $this;
    }
设置最后修改时间.

@param \DateTime $datetime

@return $this