Yii use file upload class

https://segmentfault.com/a/1190000009674814

Link above article has been written by a very good, clear, do not be explained here.

Added: When performing 

UploadedFile-> saveAs ($ file) This method of time, $ file address this argument can not be /upload/xxx/xx.jpg only upload / xxx / xx.jpg is not put in front of the slash / \