There is a similar app back in China, which was my all time favorite. However, Im not able to use that app here in the US. Fortunately, my friend recommended Muzix Cloud Pro to me. I have to say that this is a perfect alternative to use. Eventually I could listen to my music stored in Dropbox and Google Drive on my iPhone! Thank you Muzix Cloud!
heningz about Muzix Cloud Pro - Listen to Music And Download from your Dropbox, Google Drive (Cloud Platforms)