It has been called "the Chinese lip-syncing app your kids love, but you've never heard of", and now it has become a hit in the States. The upstart video-sharing app TikTok is the most popular free download in the App Store in the US, above such behemoths as Facebook, YouTube and Amazon. It has been downloaded almost 80m times in the US to date, including nearly 4m downloads in October alone, making it No.1 in the App Store for that month. The success of any burgeoning app is often tied to the early adoption of a key celebrity.
to date : 到现在为止