iPhone城市飞艇坠毁瞬间事件

所以，我遵循UA文档，一切都很顺利。问题是我一直在下面了解这个崩溃

Terminating app due to uncaught exception 'InstanceNotExists', reason: 'Attempted to access instance before initializaion. Please call takeOff: first.'

只有打开应用程序关闭应用程序，然后尝试重新打开，或者打开应用程序关闭应用程序，发送通知，然后尝试单击通知，才会出现这种情况。它在第一次加载时从不崩溃。我在下面安装的代码

#import "UAirship.h"
#import "UAPush.h"

 -(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
NSMutableDictionary *takeOffOptions = [NSMutableDictionary dictionary];
[takeOffOptions setValue:launchOptions forKey:UAirshipTakeOffOptionsLaunchOptionsKey];

[UAirship takeOff:takeOffOptions];

// Register for notifications
[[UAPush shared]
 registerForRemoteNotificationTypes:(UIRemoteNotificationTypeBadge |
                                     UIRemoteNotificationTypeSound |
                                     UIRemoteNotificationTypeAlert)];


-(void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
 //Updates the device token and registers the token with UA.
 NSLog(@"My token is: %@", deviceToken);
 [[UAPush shared] registerDeviceToken:deviceToken];
}

-(void)applicationWillTerminate:(UIApplication *)application
 {
  // Saves changes in the application's managed object context before the application terminates.
 [UAirship land];
 [self saveContext];

}

我错过什么了吗？任何帮助都将不胜感激！谢谢