摘要：UIViewController has several methods that get called at certain times: viewWillAppear: when its view is about to be added to the window viewDidAppear: when its view has been added to the window viewWillDisappear: when its view is about to be dismissed, covered, or otherwisehidden from view viewDidDi 阅读全文

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

摘要：Delegation is an object-oriented approach to callbacks. A callback is a function that is supplied inadvance of an event and is called every time the event occurs. Some objects need to make a callbackfor more than one event. For instance, the location manager wants to “callback” when it finds a newl. 阅读全文

摘要：If you create an object using a method whose name starts with alloc or new or contains copy, thenyou have taken ownership of it. (That is, assume that the new object has a retain count of 1 and isnot in the autorelease pool.) You have a responsibility to release the object when you no longer needit. 阅读全文

摘要：Touches have life cycles. Each touch can pass through any of five phases that represent theprogress of the touch within an interface. These phases are as follows:　　UITouchPhaseBegan—Starts when users touch the screen.　　UITouchPhaseMoved—Means a touch has moved on the screen.　　UITouchPhaseStationary— 阅读全文

摘要：Views store arrays of their children. Retrieve this array by calling [aView subviews].Onscreen, the child views are always drawn after the parent, in the order that they appearin the subviews array.These views draw in order from back to front, and the subviewsarray mirrors that drawing pattern.Views 阅读全文

摘要：[代码] 阅读全文

摘要：One of the great things about Cocoa Touch is that you don’t have to program entirely byhand or entirely using Interface Builder.You can leverage IB’s visual layout and combine itwith Xcode-based programming for a better, hybrid solution. 阅读全文

摘要：[代码] 阅读全文

摘要：The main.m file has two jobs. First, it creates a primary autorelease pool for your application.Second, it invokes the application event loop.These two elements provide critical elementsto get your ap... 阅读全文