the apps of individual banks are not honest, and the users are not clearly explained how to use them in the apps. The app of individual banks uses HCE China Unionpay Quick Pass mode, and the app interface must be opened to make the flash payment successful (in essence, the app needs to call a special service for flash payment, and the service can ensure the success of flash payment after the app is opened); Some people go even further, when they have to pay in flash, they open the bank app and connect to the Internet. (The essence is that this kind of bank app updates the key in the background networking state).

Of course, most bank app flash payments support a certain number of transactions within a period of time. Flash payment can be made without networking or opening the bank app. However, if the number of offline flash payments exceeds 9 or 1, some banks' apps are more user-friendly, and they will be prompted in the notification bar of the mobile phone that they must be updated online. Otherwise, you can't continue to pay by flash without network.