The weather function is built into the IPhone4. What can't be found in any city?

First of all, you can rest assured that this is not the reason of the mobile phone, but the biggest possibility comes from the connection between the mobile phone and the network.

On the one hand, due to the application itself, it is impossible to connect to the network normally; On the other hand, it is related to the account setting of the mobile phone, which means that the online account on the mobile phone has not been opened normally.

In this case, the first thing is to reconnect the network, such as closing the current network and reopening or replacing the network connection (WIFI and 2G/3G/4G interchange); The second is to log in to the Apple ID you applied for, and then open the weather application.