I wrote an upload photo api for ios to use:

if($_FILES["cover"]["size"] != ""){
    // do....
}else{
    echo "error!";
}

counterpart bit is also cover and post matching
, but it just happens to be error!
can"t catch the file size
of the counterparty at all. How do you explain this?
is there anything else I need to configure here or on the other side?

update
whether php can print out Content-Disposition?

POST /test.html HTTP/1.1
Host: example.org
Content-Type: multipart/form-data;boundary="boundary"

--boundary
Content-Disposition: form-data; name="field1"

value1
--boundary
Content-Disposition: form-data; name="field2"; filename="example.txt"

value2
--boundary--

can php print this message?