NSFileCoordinator正确使用沙盒Mac App Store应用程序中的sqlite日志文件

Question

由于sqlite执行事务的方式(使用wal或journal文件),我有很多麻烦将我的sqlite代码移植到App Store.Apple文档的相关部分是:

您的应用程序需要能够打开或保存具有相同名称和不同扩展名的多个相关文件(例如,自动打开与电影文件同名的字幕文件,或允许SQLite日志文件).要访问该辅助文件,请创建符合NSFilePresenter协议的类.此对象应将主文件的URL作为其primaryPresentedItemURL属性提供,并应将辅助文件的URL作为其presentItemURL属性提供.用户打开主文件后,文件presenter对象应调用NSFileCoordinator类上的addFilePresenter:class方法来注册自己.

Apple DTS为我提供了以下代码:

- (void)openSQLiteFileAtURL:(NSURL *)fileURL { 
    NSFileCoordinator *fc = [[NSFileCoordinator alloc] initWithFilePresenter:nil];
    [fc coordinateReadingItemAtURL:fileURL options:0 error:NULL byAccessor:^(NSURL *newURL) {
        sqlite3 *db = NULL;
        char *zErrMsg = 0;

        [SQLiteRelatedItemPresenter addPresentersForURL:newURL];

        int rc = sqlite3_open_v2([[newURL path] fileSystemRepresentation], &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, NULL);

        NSLog(@"open %@ = %d", [newURL path], rc);

        rc = sqlite3_exec(db, "CREATE TABLE foo (col1 INTEGER);", callback, 0, &zErrMsg);
        if( rc!=SQLITE_OK ){
            NSLog(@"SQL error: %s\n", zErrMsg);
            sqlite3_free(zErrMsg);
        }

        // more sqlite code here

        sqlite3_close(db);

        }];
        return;
}

其中SQLiteRelatedItemPresenter是:

@interface SQLiteRelatedItemPresenter : NSObject <NSFilePresenter>
{
    NSURL *primaryPresentedItemURL;
    NSURL *presentedItemURL;
}

static NSOperationQueue *_presentedItemOperationQueue;

@implementation SQLiteRelatedItemPresenter

+ (void) initialize {
    [super initialize];
    if (_presentedItemOperationQueue == nil) {
        _presentedItemOperationQueue = [[NSOperationQueue alloc] init];
    }
}

+ (void)addPresentersForURL:(NSURL *)databaseURL {
    SQLiteRelatedItemPresenter *p1, *p2, *p3, *p4;

    p1 =[[SQLiteRelatedItemPresenter alloc] initWithFileURL:databaseURL prefix:nil suffix:@"-wal"];
    [NSFileCoordinator addFilePresenter:p1];
    p2 = [[SQLiteRelatedItemPresenter alloc] initWithFileURL:databaseURL prefix:nil suffix:@"-shm"];
    [NSFileCoordinator addFilePresenter:p2];
    p3 = [[SQLiteRelatedItemPresenter alloc] initWithFileURL:databaseURL prefix:nil suffix:@"-journal"];
    [NSFileCoordinator addFilePresenter:p3];
    p4 = [[SQLiteRelatedItemPresenter alloc] initWithFileURL:databaseURL prefix:@"." suffix:@"-conch"];
    [NSFileCoordinator addFilePresenter:p4];

    // +filePresenters will only return once the asynchronously added file presenters are done being registered
    [NSFileCoordinator filePresenters];
}

- initWithFileURL:(NSURL *)fileURL prefix:(NSString *)prefix suffix:(NSString *)suffix {
    self = [super init];
    if (self) {
        primaryPresentedItemURL = fileURL;
        NSString *path = [fileURL path];
        if (prefix) {
            NSString *name = [path lastPathComponent];
            NSString *dir = [path stringByDeletingLastPathComponent];
            path = [dir stringByAppendingPathComponent:[prefix stringByAppendingString:name]];
        }
        if (suffix) {
            path = [path stringByAppendingString:suffix];
        }
        presentedItemURL = [NSURL fileURLWithPath:path];
    }
    return self;
}

- (NSURL *)presentedItemURL {
    return presentedItemURL;
}

- (NSOperationQueue *)presentedItemOperationQueue {
    return _presentedItemOperationQueue;
}

- (NSURL *)primaryPresentedItemURL {
    return primaryPresentedItemURL;
}

此特定示例适用于所有在openSQLiteFileAtURL方法内执行的sqlite操作.如果我尝试将逻辑划分为子方法,我会遇到很多麻烦,例如:

- openSQLiteFileAtURL:(NSURL *)databaseURL; // just open the db
- executeSQLStatement:(NSString *)sql; //perform read/write operations into the sqlite db previously opened in the openSQLiteFileAtURL method
- closeSQLite(); //close db method.

似乎addPresentersForURL应该只被调用一次(在openSQLiteFileAtURL中)但由于沙盒权限错误,我无法拥有一个有效的应用程序...任何帮助？