iOS provides lots of small icons—representing common tasks and types of content—for use in navigation bars, tab bars, toolbars, and Home screen quick actions. It’s a good idea to use these built-in icons as much as possible because they're familiar to people.
Provide alternative text labels for icons. Alternative text labels aren’t visible onscreen, but they let VoiceOver audibly describe what's onscreen, making navigation easier for people with visual impairments.
Navigation Bar and Toolbar Icons
Tip You can use text instead of icons to represent items in a navigation bar or toolbar. For example, Calendar uses “Today,” “Calendars,” and “Inbox” in the toolbar. You can also use a fixed space element to provide padding between navigation and toolbar icons.
For developer guidance, see UIBarButtonItem.
Tab Bar Icons
For developer guidance, see UITabBarItem.
Quick Action Icons
For developer guidance, see UIApplicationShortcutIcon.