之前很奇怪app启动之后的广告展示是怎么处理的，特意试了下效果，下面是我简单实现的一个广告展示效果代码如下：在AppDelegate.h中的代码

#import <UIKit/UIKit.h>
 
@interface AppDelegate : UIResponder <UIApplicationDelegate>
 
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) UIImageView *adImageView;
@property (strong, nonatomic) UINavigationController *rootNavi;
 
@end 

在AppDelegate.m中的代码

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen]bounds]];
    // Override point for customization after application launch.
    AlertDemoViewController *vc = [[AlertDemoViewController alloc]init];
    
    UINavigationController *navi = [[UINavigationController alloc]initWithRootViewController:vc];
    
    if (isIOS7) {
        [navi.navigationBar setBarTintColor:[UIColor clearColor]];
    }else{
        [navi.navigationBar setTintColor:[UIColor clearColor]];
    }
    self.rootNavi = navi;
    
    //self.window.rootViewController = navi;
    
    self.adImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, [[UIScreen mainScreen] bounds].size.width, [[UIScreen mainScreen]bounds].size.height)];
    [self.adImageView setImage:[UIImage imageNamed:@"tmplecture"]];
    [self.window addSubview:self.adImageView];
    [self performSelector:@selector(removeAdImageView) withObject:nilafterDelay:3];
    
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}
 
- (void)removeAdImageView
{
    [UIView animateWithDuration:0.3f animations:^{
        self.adImageView.transform = CGAffineTransformMakeScale(0.5f,0.5f);
        self.adImageView.alpha = 0.f;
    } completion:^(BOOL finished) {
        [self.adImageView removeFromSuperview];
        self.window.rootViewController = self.rootNavi;
    }];
}

淡入淡出更换 rootViewController

- (void)restoreRootViewController:(UIViewController *)rootViewController
{
 typedef void (^Animation)(void);
 UIWindow* window = self.window;
  
 rootViewController.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
 Animation animation = ^{
  BOOL oldState = [UIView areAnimationsEnabled];
  [UIView setAnimationsEnabled:NO];
  window.rootViewController = rootViewController;
  [UIView setAnimationsEnabled:oldState];
 };
  
 [UIView transitionWithView:window
       duration:0.5f
        options:UIViewAnimationOptionTransitionCrossDissolve
     animations:animation
     completion:nil];
}