Programming iOS 4

Chapter 25. Controls and Other Views

This chapter discusses all UIView subclasses provided by UIKit that haven’t been discussed already (except for the two modal dialog classes, which are described in the next chapter). It’s remarkable how few of them there are; UIKit exhibits a noteworthy economy of means in this regard.

Additional UIView subclasses are provided by other frameworks. For example, the Map Kit framework provides the MKMapView (Chapter 34). Also, additional UIViewController subclasses are provided by other frameworks as a way of creating interface. For example, the MessageUI framework provides MFMailComposeViewController, which acts as a contained view controller to give your app interface for letting the user compose and send a mail message (Chapter 33). There will be lots of examples in Part VI.

UIActivityIndicatorView

An activity indicator (UIActivityIndicatorView) appears as the spokes of a small wheel. You set the spokes spinning with startAnimating, giving the user a sense that some time-consuming process is taking place. You stop the spinning with stopAnimating. If the activity indicator’s hidesWhenStopped is YES (the default), it is visible only when spinning.

An activity indicator comes in a style, its activityIndicatorViewStyle; if the indicator is created in code, you’ll set its style with initWithActivityIndicatorStyle:. Your choices are:

• UIActivityIndicatorViewStyleWhiteLarge
• UIActivityIndicatorViewStyleWhite
• UIActivityIndicatorViewStyleGray

An activity ...