iPhone NavigationController 堆栈的 NSCoding 序列化

Question

编辑：我似乎找到了一些有用的东西。我保留了 ivar “堆栈”，现在它似乎可以工作了

我一直在序列化几个自定义 NSObject 类而没有问题。现在我想序列化我的 NavigationController 堆栈。每个 viewController 只需要保存几个属性即可重建导航树。我已经在 viewControllers 中实现了 NSCoding 协议，并成功地将它们编码为 NSData 并保存到磁盘。

当我尝试加载堆栈时，生成的数组具有正确数量的对象，但是当我尝试设置 viewController 数组时，我不断收到 EXC_BAD_ACCESS 错误。我是不是走错了路？

//AppDelegate.m
-(void) loadDataFromDisk {
   NSString *libraryPath = [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) objectAtIndex:0];
   NSString *programDataPath = [libraryPath stringByAppendingPathComponent:@"programData.dat"];
   NSData *programData = [[NSData alloc] initWithContentsOfFile:programDataPath];
   NSKeyedUnarchiver *decoder = [[NSKeyedUnarchiver alloc] initForReadingWithData:programData];
   //stack is a mutable array declared in header
   //stack = [decoder decodeObjectForKey:@"stack"];
       stack = [[decoder decodeObjectForKey:@"stack"]retain]; //retain fixes? Seems to work
   [decoder release];
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
   // Override point for customization after app launch    
   [window addSubview:[navigationController view]];
   [window makeKeyAndVisible];
   NSLog(@"%@",self.navigationController.viewControllers);
   if ([stack count] > 1) {
           self.navigationController.viewControllers = stack;
           [stack release];  //retained earlier
   }
   return YES;

}

Answer 1

从磁盘加载后，我必须保留 viewController 堆栈。显然，如果您不立即将数据分配给保留的属性，它就会消失。