最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
The navigation bar contains the navigation buttons for the navigation controller. The title in the navigation bar is the title of the current view controller. 1.创视图应用程序 Now, select the application Delegate.h and add the properties of the navigation controller, as follows: 3. 更新应用程序: didFinishLaunchingWithOptions:方法，在AppDelegate.m文件分配的导航控制器，并使其成为窗口的根视图控制器，如下所示： 4.现在，通过选择 File -> New -> File… -> Objective C Class add a new class file, TempViewController, and name the class as a subclass of TempViewController and UIViewController. 5.在ViewController.h中添加navButon，如下所示 6.现在添加方法addNavigationBarItem并在viewDidLoad调用方法 Create methods for navigation items We also need to create another method to another view controller TempViewController. The updated ViewController.m is as follows: Now when we run the application, we get the following output Click the MyButton navigation button to toggle the navigation button visibility Click the navigation button to display another view controller, as shown below 9.15.1. Sample code and steps ¶
#import - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc] initWithFrame: [[UIScreen mainScreen] bounds]]; // Override point for customization after application launch. self.viewController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil]; //Navigation controller init with ViewController as root UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:self.viewController]; self.window.rootViewController = navController; [self.window makeKeyAndVisible]; return YES; }
// ViewController.h #import
// ViewController.m #import "ViewController.h" #import "TempViewController.h" @interface ViewController () @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; [self addNavigationBarButton]; //Do any additional setup after loading the view, typically from a nib } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } -(IBAction)pushNewView:(id)sender{ TempViewController *tempVC =[[TempViewController alloc] initWithNibName:@"TempViewController" bundle:nil]; [self.navigationController pushViewController:tempVC animated:YES]; } -(IBAction)myButtonClicked:(id)sender{ // toggle hidden state for navButton [navButton setHidden:!nav.hidden]; } -(void)addNavigationBarButton{ UIBarButtonItem *myNavBtn = [[UIBarButtonItem alloc] initWithTitle: @"MyButton" style:UIBarButtonItemStyleBordered target: self action:@selector(myButtonClicked:)]; [self.navigationController.navigationBar setBarStyle:UIBarStyleBlack]; [self.navigationItem setRightBarButtonItem:myNavBtn]; // create a navigation push button that is initially hidden navButton = [UIButton buttonWithType:UIButtonTypeRoundedRect]; [navButton setFrame:CGRectMake(60, 50, 200, 40)]; [navButton setTitle:@"Push Navigation" forState:UIControlStateNormal]; [navButton addTarget:self action:@selector(pushNewView:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:navButton]; [navButton setHidden:YES]; } @end
