////  main.m//  Hello////  Created by lishujun on 14-8-28.//  Copyright (c) 2014年 lishujun. All rights reserved.//#import <UIKit/UIKit.h>// --------------视图控制器对象--------------@interface HelloWorldViewController : UIViewController@end@implementation HelloWorldViewController-(void) loadView{    NSLog(@"load View");    //创建视图对象    UIView *contentView = [[UIView alloc]initWithFrame:[[UIScreen mainScreen] applicationFrame]];    contentView.backgroundColor = [UIColor lightGrayColor];    self.view = contentView;        //设置导航栏按钮，被加载的到UINavigationController才可以使用这个属性？    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Next" style:UIBarButtonItemStylePlain target:self action:@selector(pushView:)];    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Prev" style:UIBarButtonItemStylePlain target:self action:@selector(popView:)];}-(void) pushView:(id)sender{    NSLog(@"push view");    [self.navigationController pushViewController:[[HelloWorldViewController alloc]init] animated:YES];}-(void) popView:(id)sender{    NSLog(@"pop view");    [self.navigationController popViewControllerAnimated:YES];}@end// ----------------委托对象--------------------@interface HelloWorldAppDelegate : NSObject <UIApplicationDelegate>{    IBOutlet UIWindow *window;}@property (nonatomic, retain) UIWindow *window;@property (nonatomic, retain) UINavigationController *nav;@end@implementation HelloWorldAppDelegate@synthesize window;@synthesize nav;-(void) applicationDidFinishLaunching:(UIApplication *)application{    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen]bounds]];    HelloWorldViewController *viewController = [[HelloWorldViewController alloc]init];        self.nav = [[UINavigationController alloc]initWithRootViewController: viewController];    self.window.rootViewController = self.nav;    [self.window makeKeyAndVisible];}@end// ---------------程序入口---------------------int main(int argc, char * argv[]){    @autoreleasepool {        return UIApplicationMain(argc, argv, nil, @"HelloWorldAppDelegate");    }}