cocoa-touch - iOS/iPhone SDK : initWithCoder and encodeWithCoder not being called

Question

我正在尝试保存一个名为 queueArray 的 NSMutableArray，以便在应用程序退出后可以再次加载它。我使用了一些教程来帮助我前进，这是我想出的代码。问题似乎是“initWithCoder”和“encodeWithCoder”没有被调用，没有 NSLog 调用，也没有在断点处停止。我已将 NSCoding 协议(protocol)添加到 .h 文件，我知道 queueArray 不是 nil，它包含 MPMediaItem。这是我用来尝试保存和加载数组的一些代码:

-(IBAction)saveQueuePressed {

     NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
     NSString *filePath = [rootPath stringByAppendingPathComponent:@"queueArray.archive"];

     //should cause encodeWithCoder to be called
     [NSKeyedArchiver archiveRootObject:queueArray toFile:filePath];

}

-(IBAction)loadQueuePressed {

     NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
     NSString *filePath = [rootPath stringByAppendingPathComponent:@"queueArray.archive"];

     //should cause initWithCoder to be called
     queueArray = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];

}

-(void)encodeWithCoder:(NSCoder *)coder {

     NSLog(@"encodeWithCoder");

     [coder encodeObject:queueArray forKey:@"savedQueueArray"];
}



-(id)initWithCoder:(NSCoder *)decoder {

     NSLog(@"initWithCoder");

     queueArray = [decoder decodeObjectForKey:@"savedQueueArray"];

     return self;

}

任何帮助将不胜感激!

Answer 1

encodeWithCoder: 和 initWithCoder 方法在您存档/取消存档响应它们的对象时被调用。据我了解，您的类中有这些方法，但您实际归档的对象 (queueArray) 不是该类的实例，它是一个 NSMutableArray。

如果你想保存你的整个对象，你可以改变你的 saveQueue 方法

-(IBAction)saveQueuePressed {

    NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *filePath = [rootPath stringByAppendingPathComponent:@"queueArray.archive"];

    // saving the array shouldn't, but saving the self object
    //should cause encodeWithCoder to be called:
    [NSKeyedArchiver archiveRootObject:self toFile:filePath];
}

但是如果你只想保存数组，我想你可以只使用saveQueuePressed和loadQueuePressed，我认为你不需要encode/初始化 WithCoder: 方法

更新:也许你的路不对。尝试

NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *filePath = [[rootPath stringByAppendingPathComponent:@"queueArray.archive"] stringByExpandingTildeInPath]];