ios - NSKeyedArchiver 不保存自定义对象属性

Question

我在使用 NSKeyedArchiver 时遇到问题。我正在尝试归档一个字典，它又包含自定义对象、专辑和歌曲的数组。

Album 和 Song 都是 NSObject 固有的，并且符合 NSCoding 协议(protocol)。以下是我如何实现该协议(protocol):

专辑实现文件:

-(id)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];

    self.title = [aDecoder decodeObjectForKey:@"title"];
    self.artistName = [aDecoder decodeObjectForKey:@"artistName"];
    self.songs = [aDecoder decodeObjectForKey:@"songs"];

    return self;
}

-(void)encodeWithCoder:(NSCoder *)aCoder {
    [aCoder encodeObject:self.title forKey:@"title"];
    [aCoder encodeObject:self.artistName forKey:@"artistName"];
    [aCoder encodeObject:self.songs forKey:@"songs"];
}

歌曲实现文件:

-(id)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];
    self.title = [aDecoder decodeObjectForKey:@"title"];
    self.artistName = [aDecoder decodeObjectForKey:@"artistName"];

    return self;
}

-(void)encodeWithCoder:(NSCoder *)aCoder {
    [aCoder encodeObject:self.title forKey:@"title"];
    [aCoder encodeObject:self.artistName forKey:@"artistName"];
}

title 和 artistName 属性都是 NSString，white songs 属性是一个 Song 对象数组。

我将这些对象的数组放入名为 ipodDictForArchiving 的字典中，然后像这样归档字典:

-(NSData *)dataForClient {
    NSMutableData *data = [[NSMutableData alloc] init];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    [archiver encodeObject:[self ipodDictForArchiving] forKey:kDataArchive];
    [archiver finishEncoding];
    NSLog(@"encoded dictionary");
    return data;
}

然后我像这样取消存档字典:

-(NSDictionary *)unarchiveData:(NSData *)data {
    NSData *clientData = data;
    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:clientData];
    NSDictionary *myDictionary = [unarchiver decodeObjectForKey:kDataArchive];
    [unarchiver finishDecoding];

    return myDictionary;
}

出于某种原因，字典包含 Song 和 Album 对象，但这些对象的属性返回 null。我无法弄清楚任何帮助，非常感谢!!

谢谢

Answer 1

您实现 initWithCoder 的方式不正确，应该如下所示:

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

    Album *al = [[Album alloc] init];

    al.title = [[[NSString alloc] initWithString:[aDecoder decodeObjectForKey:@"title"]] autorelease];
    al.artistName = [[[NSString alloc] init] initWithString:[aDecoder decodeObjectForKey:@"artistName"]] autorelease];
    al.songs = [[[NSArray alloc] initWithArray:[aDecoder decodeObjectForKey:@"songs"]] autorelease];

    return al;
}

歌曲也一样。

[编辑] 而且您存档相册的方式似乎不正确，让我们尝试更简单的方式:

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:album];

然后您可以保存此数据以便稍后取消存档。