Wi Fi and mobile data are two different frequency bands that do not conflict with each other, so they can be turned on simultaneously. If you open the Wi Fi and move data at the same time, the phone will first default to connect Wi Fi, disconnect the Wi Fi will connect to the data network.
Is that safe and bold to drive 4G?
Of course not, Although 4G/3G traffic data is not generated when using Wi Fi, the phone switches to the 4G/3G mode automatically when the Wi Fi signal is disconnected or is not good. If we are using some software to play video, music, or when we update the software, the system may use your traffic.
Of course, some software will prompt you when Wi Fi breaks: do you use 4G/3G data to watch? But that doesn't mean all software alerts. So we need to set up a cellular mobile network: disable some video, music and other software that consumes traffic, and disable running in 4G/3G. So you don't have to worry about it.
Is that 4G open or not?
Actually, this problem needs to be divided into two parts.
If you worry that the wireless network is disconnected, the system will steal data traffic, you'd better turn off the data; if you cannot afford to shut the habit of customs, take a look at the top of the phone icon.
But if you're worried that Wi Fi will lose contact when it breaks, or if you have too much traffic, you can open them at the same time. You can also open the "Wi Fi assistant" in the iPhone settings so that you can automatically use the honeycomb data when the Wi Fi signal is weak. However, be reminded to change the settings of the cellular data by referring to second points.