iphone - writeToFile 原子地返回 NO

Question

我有以下代码:

NSString *errorStr = nil;
NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:dict
                                                               format:NSPropertyListBinaryFormat_v1_0
                                                     errorDescription:&errorStr];
if (errorStr) {
    // Darn.
    NSLog(@"saving dictionary error %@", errorStr);
} else {
    // [plistData writeToFile:file atomically:YES];
    // (ankit): Changing this to NO for speed.
    success = [plistData writeToFile:file atomically:NO];
}

然而，对于以下字典，这将返回 NO:

  {
    entries = (
                {
            author = "Jada Wong";
            cellIdentifier = default;
            date = "2012-10-15 02:22:41 +0000";
            domain = Readability;
            feedUrl = "readability://feed";
            imagesAreOnPulsesubscriber = 0;
            order = 0;
            summary = "";
            templateUrl = "default_template.html";
            title = "We\U2019re Going To Try Out Dolce & Gabbana\U2019s Beauty Look This Weekend";
            url = "http://www.styleite.com/media/styledish-10122012/";
        }
    );
}

但它适用于以下字典:

{
    entries =     (
                {
            author = "Colleen Taylor";
            cellIdentifier = default;
            date = "2012-10-15 01:00:05 +0000";
            domain = TechCrunch;
            domainUrl = "http://techcrunch.com";
            feedUrl = "http:/asdasdm/TechCrunch";
            images =             (
                "http://asdshot-2012-10-14-at-5-20-43-pm.png"
            );
            imagesAreOnPulsesubscriber = 1;
            lastUpdated = 1350263095;
            order = 0;
            shortLink = "http://bete.me/s/ej2Tg";
            summary = "Bonobos, the men's clothing company, has gained lots of ground since it was founded in 2007 for its presence on the web as a mostly pure e-commerce p...";
            templateUrl = "default_template.html";
            title = "Inside Bonobos\U2019 New Palo Alto Digs, Where The Startup Known For E-Commerce Is Investing In Bricks & Mortar";
            url = "http://techcrunch.com/2012/10/14/bonobos-palo-alto-mike-hart/";
        }
    );
}

知道为什么吗？它适用于不同的字典我写入的文件路径是:

/var/mobile/Applications/4B60A704-BE00-4160-BFB4-AD89187FADD1/Library/Caches/StoryCache/readability:  feed

我得到的错误是:

"The operation couldn\u2019t be completed. (Cocoa error 512.)" UserInfo=0xb41580 {NSFilePath=/var/mobile/Applications/4B60A704-BE00-4160-BFB4-AD89187FADD1/Library/Caches/StoryCache/readability:  feed, NSUnderlyingError=0xbb8930 "The operation couldn\u2019t be completed. Is a directory"}

Answer 1

使用 writeToFile:options:error: 而不是 writeToFile:atomically: 以便记录错误代码。

NSError *error;
success = [plistData writeToFile:file options:0 error:&error];
if (!success) {
    NSLog(@"writeToFile failed with error %@", error);
}

更新

根据您粘贴到问题中的错误，我猜您已经有一个名为 /var/mobile/Applications/4B60A704-BE00-4160-BFB4-AD89187FADD1/Library/Caches/StoryCache/readability: feed 的目录。您不能用文件覆盖目录。您需要先重命名或删除该目录。您可以使用 -[NSFileManager removeItemAtPath:error:] 递归删除目录及其所有内容。