UITabbar vs UIToolbar

For iOS, the guideline summaries are:

Navigation Bars:

A navigation bar appears at the top of an app screen, below the status bar, and enables navigation through a series of hierarchical screens.

Toolbars:

A toolbar appears at the bottom of an app screen and contains buttons for performing actions relevant to the current view or content within it.

Tab Bars:

A tab bar appears at the bottom of an app screen and provides the ability to quickly switch between different sections of an app.

As far as advantages and disadvantages of each, one important aspect is whether you want the bar to appear at the top or bottom of a view. Navigation bars are supposed to appear at the top, while toolbars and tab bars are expected to appear at the bottom of the view.

Another is whether you want navigation functionality vs actions/tasks related to a view.

Navigation Bars implement a button to return to the previous view in the stack, tab bars provide a more abrupt change (such as switching from an alarm view to a timer view, say), and toolbars are really intended for actions (such as sharing, say) rather than actual "navigation".

 

 

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Tabbar

If your application provides different perspectives on the same set of data, or different subtasks related to the overall function of the application, you might want to use a tab bar. A tab bar appears at the bottom edge of the screen.

A tab bar gives users the ability to switch among different modes or views in an application, and users should be able to access these modes from everywhere in the application

Toolbar

If your application provides a number of actions users can take in the current context, it might be appropriate to provide a toolbar