Ray's playground

摘要： Every UIView subclass implements the method drawRect:, which contains the drawing code for theview. For example, a UIButton’s drawRect: method draws a rounded rectangle with a title string in thecenter. Each time an instance of UIView needs to be drawn (or redrawn), the system prepares a graphicsco. 阅读全文

摘要： The Core Location framework tells us where we are in the world; the MapKit framework shows usthat world. Most of MapKit’s work is done by the class MKMapView. Instances of this type display amap, track touches, and display annotations. 阅读全文