bluetooth99 2013-01-08 01:54 采纳率: 0%
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报错:nil modal view controller

得到了如下报错:**Application tried to present a nil modal view controller on target**。我在运行的程序是,首先判断条件是否满足,启动后修改初始化视图控制器。

   - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:( NSDictionary *)launchOptions
 {
 if(![[NSUserDefaults standardUserDefaults] boolForKey:@"logged_in"]) {
    ViewControllerOne *vc1 = [[ViewControllerOne alloc]init];
    vc1=[self.storyboard instantiateViewControllerWithIdentifier: @"vc1"];
    [self presentViewController:vc1 animated:YES completion:Nil];
    } else {

    ViewControllerTwo *vc2 = [[ViewControllerTwo alloc]init];
    vc2=[self.storyboard instantiateViewControllerWithIdentifier: @"vc2"];

    [self presentViewController:vc2 animated:YES completion:Nil];
}
// Override point for customization after application launch.
return YES;
}
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2条回答 默认 最新

  • ReyZhang 移动开发领域新星创作者 2013-01-08 03:56
    关注

    如果是从storyboard中来创建控制器不需要先

    ViewControllerOne *vc1 = [[ViewControllerOne alloc]init];
    

    修改后的代码如下:

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    {
         UIViewController *rootVC;
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        self.window.backgroundColor = [UIColor whiteColor];
        if(![[NSUserDefaults standardUserDefaults] boolForKey:@"logged_in"]) {
               rootVC=[self.storyboard instantiateViewControllerWithIdentifier: @"vc1"];
        } else {
               rootVC=[self.storyboard instantiateViewControllerWithIdentifier: @"vc2"];
         }
        window.rootViewConroller=rootVC;
        [self.window makeKeyAndVisible];
        return YES;
    }
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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