If you need/want to track and bill your time, you may be looking for an iOS app that works with and syncs to your Mac/PC. You should consider OfficeTime. This app allows you to set up projects and categories of billing events to quickly capture the time you spend with all of the details identified.
You can even capture expenses and track your time while you are on the go with your iOS device. View reports of time spent on various projects on your iOS device.
When you get back to the office, you can sync to the separate Mac/PC app. The process is painless as long as you are on the same wireless network when attempting to sync.
Once the information is on your Mac, you can then create invoices, reports and more.
If you are interested in learning more about the apps, contact OfficeTime.