iOS 5 Programming Cookbook

2.23. Displaying Progress with UIProgressView

Problem

You want to display a progress bar on the screen, depicting the progress of a certain task, for instance, the progress of downloading a file from a URL.

Solution

Instantiate a view of type UIProgressView and place it on another view.

Discussion

A progress view is what programmers generally call a progress bar. An example of a progress view is depicted in Figure 2-74.

Figure 2-74. A simple progress view

Progress views are generally displayed to users to show them the progress of a task that has a well-defined starting and ending point. For instance, downloading 30 files is a well-defined task with a specific starting and ending point. This task obviously finishes when all 30 files have been downloaded. A progress view is an instance of UIProgressView and is initialized using the designated initializer of this class, the initWithProgressViewStyle: method. This method takes in the style of the progress bar to be created as a parameter. This parameter is of type UIProgressViewStyle and can therefore be one of the following values:

UIProgressViewStyleDefault

This is the default style of the progress view. An example of this is the progress view shown in Figure 2-74.

UIProgressViewStyleBar

This is similar to the UIProgressViewStyleDefault but is meant to be used for progress views that are to be added to a toolbar.

An instance of UIProgressView ...