Here is a site that features apps (iOS) and teacher training videos for their programs. They seem to focus on HSK (漢語水平考試) test preparation, too. Since you have to pay for apps, likely I will not be reviewing any of them specifically (unless they are free or I find them super useful). The link takes you straight to their app page.
Hua Yu School – Company developed an e-learning teaching system and create related products (Eg: books, workbooks, training videos). They focus on creating Chinese learning materials for foreigners, Chinese learning materials, Chinese mobile programs, and Chinese online learning website. You need to pay or sign up for access to the training videos.
Site Language: English
Physical Location: No
Type: iOS, web
Products: Teacher training videos, Chinese learning for foreigners, Chinese learning materials, Chinese mobile programs, and Chinese online learning website, apps (business, children, culture), prep materials
Product Languages: Traditional, Simplified, English, pinyin