如何使用 NSKeyedArchiver 存储 CLLocation 对象？

Question

我有点困惑为什么以下不起作用。有人能启发我吗？

我有一个返回filePath的函数：

- (NSString *) lastLocationPersistenceFilePath {
    NSString *filePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingString:@"last_location"];
    return filePath;
}

然后，在按钮触发的方法中，我尝试像这样保存CLLocation 对象：

// Store this location so it can persist:
BOOL success = [NSKeyedArchiver archiveRootObject:_startLocation toFile:[self lastLocationPersistenceFilePath]];
if (!success) {
    NSLog(@"Could not persist location for some reason!");
} else {
    NSLog(@"New location has been stored.");
}

在我的viewDidLoad: 中，我尝试加载它：

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Retrieve last location:
    CLLocation *decodedLocation = [NSKeyedUnarchiver unarchiveObjectWithFile:[self lastLocationPersistenceFilePath]];

    if (decodedLocation) {
        _startLocation = decodedLocation;
    } else {
        NSLog(@"Decoding failed.");
    }
}

存档失败，当然，这意味着我也无法解码任何内容。我觉得我遗漏了一些明显/琐碎的东西……有什么建议吗？

Answer 1

简单地说，无法写入应用程序的资源目录。而是写入应用的文档目录。

代码示例”

- (NSString *) lastLocationPersistenceFilePath {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectory = [paths firstObject];
    NSString *filePath = [documentDirectory stringByAppendingPathComponent:@"last_location"];
    return filePath;
}