Condition: We upgrade itunes to the latest version of itunes, and then we make sure that the iphone and the computer must be in the same LAN.
First use the data cable to connect your device and computer, the new version of itunes does not display the left sidebar, need to use the keyboard shortcuts ctrl+s key Open, then select your device, the right to find options, and check the "through Wi-Fi and this iphone sync" before the checkbox:
The iphone is set up on the phone
We clicked "Settings" in the iphone as shown in the following image:
Then we set the "generic" as shown in the following figure.
Then we open the "general" list and we click on ITunes wi-Fi sync to go to confirm whether to open:
At this point you can unplug the data cable, turn off itunes and then open again, this time the "sync now" can be clicked, click Sync Start:
Okay, well, then we can use Wi-Fi to back up the data.
Of course, if you want to back up a few gigabytes of files, we'd better use the data cable. WiFi may be slower.