I've read this and many other questions. I learned that there is no way to schedule task to run from background at a specific time.
My application uses CLVisit api to send location information to the server. But I want the user to be able to select a time range to send his/her check-ins. Is there any different way to stopMonitoringVisits() and startMonitoringVisits() at a specific time from background? Should my app always monitor and decide to send the location after receiving didVisit call?
Same question can be asked for startMonitoringSignificantLocationChanges()
As long as visit monitoring does exactly what your app needs, keep the monitoring always on and decide on proper handling (whether you should report location to server) when processing didVisit callback.
You are not going to put any noticeable stress on battery this way, as visit tracking is very battery friendly and iOS runs that kind of monitoring by default with or without your app.
Furthermore, any attempt to employ some "smart" tricks designed to circumvent the good practices, which are recommended by vendor and even enforced by API design, inevitably results in "bad practices", which in your case most likely will bring extra battery consumption.
The only adverse effect of keeping monitoring always on is the solid arrow in status bar, which is considered as a sign of high battery usage by many "educated" iPhone users. If this is the primary concern, and if your use case deals with quite a few time spans (for example, leaving office and home locations), you may try to use silent push notifications to activate the monitoring at around the right time.