If you need to quickly change the time of an event or appointment in your iPhone or iPad's Calendar, the today view gives you an incredibly easy way of doing so by dragging and dropping instead of entering into edit mode for each event you need to change. Unfortunately, the Calendar app doesn't make the option very obvious. But once you know where it's at, we're pretty sure you'll prefer it over editing individual events when it comes time to plan your day.
How to move a calendar event or appointment on iPhone or iPad by dragging and dropping
Launch the Calendar app on your iPhone or iPad.
Toggle list view off at the top if it isn't already.
Tap on the day you need to switch things around for.
Press and hold on the event you need to change the time for. It will change to a darker color.
Drag the event to the time you need to move it to and release it.