无法将 NSDictionary 写入 plist 文件

Question

更新：当我更改以下行时，我可以写入文件

[infoDict setObject:userList forKey:@"users"];

到

[infoDict setObject:@"sampleString" forKey:@"users"];

所以，我尝试写入文件的结构一定有问题，有什么想法吗？

---

我正在尝试在我的 iOS 应用程序中创建一个 plist 文件并在运行时写入它。我无法写信，但我可以阅读。 writeToFile 方法返回“否”。 当我手动尝试手动打开使用 Finder 创建的文件时，它显示“无法读取数据，因为它的格式不正确。”，我理解这是因为使用文本编辑器打开文件时为空并且不显示 plist 类型的文件应具有的任何 xml 标记。 而且我知道我可以从中读取，因为在文件夹中手动拖动“有效”plist 文件时，我的代码能够从那里读取一个空列表。

1) 为什么没有创建有效的 plist 文件？

和，

2) 为什么我无法写入（甚至是有效的）plist 文件？

    NSLog(@"* Writing contents to plist file *");

    NSString* path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString* plistPath = nil;

    if ((plistPath = [path stringByAppendingPathComponent:@"users.plist"]))
    {
        NSFileManager *fileManager = [NSFileManager defaultManager];

        BOOL exists = [fileManager fileExistsAtPath:plistPath];
        NSLog(exists ? @"yes, file exists": @"no, file doesnt exist");

        if (!exists) {
            NSLog(@"creating file since it doesnt exist");
            [fileManager createFileAtPath:plistPath contents:nil attributes:nil];
        }

        NSLog(@"path of file: %@", plistPath);
        NSMutableDictionary *infoDict = [[NSMutableDictionary alloc] init];
        NSLog(@"infoDict: %@", infoDict);

        [infoDict setObject:userList forKey:@"users"];
        NSLog(@"infoDict: %@", infoDict);

        BOOL wrote = [infoDict writeToFile:plistPath atomically:YES];
        NSLog(wrote ? @"yes, wrote to the file": @"no, didn't write to file");
   }
    NSLog(@"--------------------------------------------");

以下是控制台中的输出：

    2014-10-17 10:50:11.290 UserReggy[1228:10032] * Writing contents to plist file *
2014-10-17 10:50:11.291 UserReggy[1228:10032] yes, file exists
2014-10-17 10:50:11.291 UserReggy[1228:10032] path of file: /Users/rvyas1/Library/Developer/CoreSimulator/Devices/DB612284-F481-467A-BAE8-37750497F42A/data/Containers/Data/Application/C9620C4D-EF1F-4C17-8D28-4E9B3B41F2C2/Documents/users.plist
2014-10-17 10:50:11.291 UserReggy[1228:10032] infoDict: {
}
2014-10-17 10:50:11.291 UserReggy[1228:10032] infoDict: {
    users =     {
        dfgdfgd = "<User: 0x7ffd884da820>";
    };
}
2014-10-17 10:50:11.292 UserReggy[1228:10032] no, didn't write to file
2014-10-17 10:50:11.294 UserReggy[1228:10032] --------------------------------------------

Answer 1

您可以在 userList 中检查您的数据，它必须是属性列表对象（NSData、NSDate、NSNumber、NSString、NSArray 或 NSDictionary 的实例），文档在the NSMutableDictionary Reference

Answer 2

问题在于NSMutableDictionary *infoDict = [NSMutableDictionary dictionaryWithContentsOfFile:plistPath];

它会给你空对象，因为你的 plistPath 是 nil

Answer 3

NSMutableDictionary *fileData;

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.plist"];

    NSFileManager *fileManager = [NSFileManager defaultManager];

    if ([fileManager fileExistsAtPath: path])
    {
        fileData = [[NSMutableDictionary alloc] init];
        if ([fileData initWithContentsOfFile: path])
        {
            fileData = [fileData initWithContentsOfFile: path];
        }

    }
    else
    {
        [fileManager createFileAtPath:path contents:nil attributes:nil];

        fileData = [[NSMutableDictionary alloc] initWithCapacity:0];

    }

        [fileData setObject:data forKey:qid];

    BOOL wrote = [fileData writeToFile:path atomically:YES];
    NSLog(wrote ? @"yes, wrote to the file": @"no, didn't write to file");

试试这个。为我工作。