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Understanding rejection on WeChat (Weixin)(See also URL encoder for mobile chat)
Many Chinese people now prefer to manage their contacts using a proprietary mobile messaging and social networking application called WeChat
Cache bloatThe Android version of WeChat can build up multiple gigabytes in a directory with a 32 hex-digit name under
/sdcard. These files are not the chat logs---they're just cache (and I haven't found an option to clear it; Android's built-in cache-clearing option does not affect this). Some subdirectories (e.g.
video) contain files present in chats, and removing them may make these files no longer accessible from the chat history, but it seems that at least the
snsdirectories are always safe to delete without losing any history, pictures, files or "favourites".
Image and video limitsIf pasting a scanned document into a WeChat conversation as an image, the size limit is 300KiB, after which the image is shown only as a preview and the recipient must take specific action (which might not be obvious to everyone) to download the full image.
The size limit for inline videos is just under 14MiB, and the mobile application should be used to introduce these into the WeChat network (i.e. by 'Share' or 'Send' from another mobile application)---at least some versions of the desktop application send videos as "files" that need extra action to view. Attempts to send videos larger than 14MiB on the mobile application get the error "unable to import", although the "say something" caption (if any) is sent anyway. The error "Unable to share this video due to unspported format" (e.g. if trying to post a short video to Moments) probably means you need to recode to h264.
By comparison, WhatsApp usually compresses inline images to around 250k (with no option to see full size) and limits video to 16MiB (as of 2017; best sent from the mobile application), Telegram Messenger scales down to max 1280 pixels per dimension and sends the result as an 87%-quality JPEG (unless uploaded as a file) but has a much more generous video limit, and LINE can send large JPGs but the recipient must save (to Pictures/LINE) to access resolutions higher than the zoomed-out screen (this screen's "pinch to zoom" does not add more detail), so you'd have to set a reduced DPI to avoid double-bluring.
Audio recordingsMP3 files are sent as "files" no matter what, so the desktop application can be used ("drag and drop"); if using the mobile application, shared files (unlike videos) need to be added to "WeChat Favourites" before they can reliably be sent to a chat. Once in Favourites, the option to "forward" from the "Favourites" screen is unreliable; it seems better to go into the chat itself and press the + button, scroll to the Favourites option, and find the MP3 that way. Ensure it is uploaded before deleting from Favourites. After you delete it from Favourites, you will get the message "This file is no longer available" when you try to open it in the chat, but the other party should still be able to access it for a few days.
Network effectWeChat's dominance in China was perhaps assisted by the company's good relationship with that country's network police, with its mobile operators (SIM cards with WeChat-specific data allowances are not unheard of), and with integrated shopping and payment services and "portals" to local facilities. Outside China, WeChat tends to lack these advantages, but many mainland Chinese visitors and immigrants keep using it anyway due to their existing network of contacts, and due to the convenience of WeChat's automatic contact-exchange facilities (scanning a QR Code™ seems to have become the most popular method, although a WeChat update in mid-2017 prevented the generation of QR codes while offline: if you expect patchy signal coverage, you now have to prepare by taking a screenshot of your QR code while connected, and updating this screenshot every 2--3 weeks).
They therefore put up with their data being sent through Chinese servers (which, apart from anything else, can be slow when you're outside China), with the "vanishing contacts" issue, and with WeChat's limited range of font sizes (especially on high-DPI devices) and limited functionality on the desktop. At least its sound compression ratio is reasonable.
Sometimes they'll accept an alternative installed alongside WeChat for use while they're in the UK. My current recommendation is Telegram Messenger, which is run by a non-profit, can be set to larger fonts, has a good range of desktop clients, etc. But not everyone even understands what it means to install a different application. Some of the older generation I met evidently had it installed by the manufacturer, a shop, or a friend or relative, and don't know what I mean by "install something else". Additionally, some older devices (e.g. iOS 4.x) cannot run recent versions of many applications, so it would be necessary to find an old version and somehow 'side-load' it, or risk an OS replacement.
ScamsAs with any form of messaging, it's probably best not to accept an `add' if you don't know who it is, especially if you actually visit an Asian country: con artists have reportedly tricked victims into going to a particular location for a "first meeting in person", only to be held to ransom by gangsters on arrival (this crime is easier to commit in small countries like Singapore). In June 2016 my WeChat ID (which I had given only to selected Chinese people I met in Cambridge) suddenly received an `add' request claiming to be from Malaysia and not giving me any clue who it was; to give them the benefit of the doubt I wrote "Apa khabar?" but received no reply and the next day eight other anonymous "Malaysians" had tried to add me. I find this highly suspicious. My ID could have been found via brute-force search, most likely of QQ numbers: I had my old QQ number linked to the account, but disabled "find by QQ ID" after this incident because I believe none of my genuine earlier contacts who had my QQ number are still likely to use it to find me.
MalwareOn iOS, a pre-6.2.6 version of WeChat was infected by malware due to its developers having accidentally downloaded "XcodeGhost" instead of Xcode. Additionally, we don't know what Tencent itself does with the information WeChat can read, so it's probably best to avoid storing things like company-confidential documents on the same device, just in case.
Disclaimer: The notes on this page are provided in the hope that they are useful, but they are not official instructions and may contain mistakes. Your use of them is at your own risk.
All material © Silas S. Brown unless otherwise stated.