Question

我遇到了NSKeyedArchiver的问题，现在已经困扰了我很长一段时间，似乎无法查明错误。

我有一个由类“Device”的对象组成的可变数组。在我的appDelegate中，我保留了一个mutableArray的设备，我有以下三个功能：

- (void) loadDataFromDisk {
    self.devices = [NSKeyedUnarchiver unarchiveObjectWithFile: self.docPath];
    NSLog(@"Unarchiving");
}

- (void) saveDataToDisk {
    NSLog(@"Archiving");
    [NSKeyedArchiver archiveRootObject: self.devices toFile: self.docPath];
}

- (BOOL) createDataPath {
    if (docPath == nil) {
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
        NSString *docsDir = [paths objectAtIndex:0];
        self.docPath = [docsDir stringByAppendingPathComponent: @"devices.dat"];
        NSLog(@"Creating path");
    }

    NSLog(@"Checking path");

    NSError *error;
    BOOL success = [[NSFileManager defaultManager] createDirectoryAtPath: docPath withIntermediateDirectories: YES attributes: nil error:&error];
    if (!success) {
        NSLog(@"Error creating data path: %@", [error localizedDescription]);
    }
    return success;
}

我一直从unarchiving过程中获得一个空的mutableArray。我正在使用ARC，不确定它是否与它有任何关系。

Answer 1

显然，我不知道的是你必须首先将你的根对象（在本例中是一个数组）保存到NSMutableDictionnary。

NSMutableDictionary *rootObject;
rootObject = [NSMutableDictionary dictionary];

[rootObject setValue: self.devices forKey: @"devices"];

然后使用NSKeyedArchiver保存rootObject。很奇怪，在任何教程中都没见过。

因此，您最终会使用以下函数将数据加载并保存到NSKeyedArchiver。

- (void) loadArrayFromArchiver {
    NSMutableDictionary *rootObject = [NSKeyedUnarchiver unarchiveObjectWithFile: [self getDataPath]];

    if ([rootObject valueForKey: @"devices"]) {
        self.devices = [rootObject valueForKey: @"devices"];
    }

    NSLog(@"Unarchiving");
}

- (void) saveArrayToArchiver {
    NSLog(@"Archiving");

    NSMutableDictionary *rootObject = [NSMutableDictionary dictionary];

    [rootObject setValue: self.devices forKey: @"devices"];

    [NSKeyedArchiver archiveRootObject: rootObject toFile: [self getDataPath]];
}

- (NSString *) getDataPath {
    self.path = @"~/data";
    path = [path stringByExpandingTildeInPath];
    NSLog(@"Creating path");
}

iOS NSKeyedArchiver unarchive返回空数组

1 个答案: