Version 2.17.40 of WhatsApp is the first to allow any file type to be sent using the Document option in the Share menu. Previously files were limited to PDF documents, but now the only limitation is file size, which is officially 100MB.
It's also now possible to pin chats to the top of the chat list to quickly find important conversation threads. To pin a chat, swipe right on the chat and tap the pin icon. Additionally, users can now tap and hold on groups of multiple photos they've received to quickly forward or delete them.
Version 2.17.40 also includes a couple of new hidden features that still appear to be in testing, suggesting they'll soon become public in a forthcoming update. According to WABetaInfo, they include in-line YouTube video playback with Picture-in-Picture support and an emoji search function.
Finally, a new Recall feature is expected to be enabled in 2.17.40+ that allows users to delete texts, images, videos, GIFs, documents, quoted messages, and even Status replies after they have been sent, as long as the Recall feature is used within a five-minute window.
WhatsApp is a free download for iPhone from the App Store. [Direct Link]