ios - 无法在文档目录的子文件夹中创建 sqlite 数据库

Question

我正在尝试在我的 iOS 应用程序中使用 Sqlite3 创建数据库。如果我在文档目录的子文件夹中创建数据库，则它不会创建数据库，而是无法打开或创建数据库。如果我不在子文件夹中创建数据库，而是直接在文档目录中创建它。它正在正确创建它。

它给出的路径为databasePath:“/var/mobile/Containers/Data/Application/986037DB-6FA0-4066-9977-C5D7A075C5E7/Documents/MailFolder/INBOX.db”但它失败了 -> if (sqlite3_open(dbpath, &database) == SQLITE_OK) –下面是我在子文件夹中创建数据库的代码。有人可以纠正我这里出了什么问题吗？

- (BOOL) createFolderMailDB :(NSString *) dbName {
    NSString *docsDir;
    NSArray *dirPaths;

    // Get the documents directory
    dirPaths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
    //docsDir =[[dirPaths objectAtIndex:0] stringByAppendingPathComponent:@"MailFolder"];
    NSString *documentsPath = [dirPaths objectAtIndex:0];
    docsDir = [documentsPath stringByAppendingPathComponent:@"/MailFolder"];

    //docsDir = dirPaths[0];
    // Build the path to the database file
    NSMutableString *finalDBPath = [[NSMutableString alloc]init];
    [finalDBPath appendString:dbName];
    [finalDBPath appendString:@".db"];
    databasePath = [[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent: finalDBPath]];

    NSLog(@"databasePath: %@", databasePath);

    BOOL isSuccess = YES;

    NSFileManager *filemgr = [NSFileManager defaultManager];
    if ([filemgr fileExistsAtPath: databasePath] == NO)
    {
        const char *dbpath = [databasePath UTF8String];
        if (sqlite3_open(dbpath, &database) == SQLITE_OK)
        {
            char *errMsg;
            const char *sql_stmt = "create table if not exists MailFolderDBTable (emailid text, foldername text, messagedata text)";
            if (sqlite3_exec(database, sql_stmt, NULL, NULL, &errMsg)
                != SQLITE_OK)
            {
                isSuccess = NO;
                NSLog(@"Failed to create table");
            }
            sqlite3_close(database);
            return  isSuccess;
        }
        else {
            isSuccess = NO;
            NSLog(@"Failed to open/create database");
        }
    }

    return isSuccess;
}

Answer 1

放置此数据库的文件夹必须存在，否则尝试在其中创建数据库将会失败。因此，在继续创建数据库之前创建该文件夹:

NSString *documentsPath  = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *databaseFolder = [documentsPath stringByAppendingPathComponent:@"MailFolder"];
NSFileManager *filemgr   = [NSFileManager defaultManager];

if (![filemgr fileExistsAtPath:databaseFolder]) {
    NSError *error;
    if (![filemgr createDirectoryAtPath:databaseFolder withIntermediateDirectories:FALSE attributes:nil error:&error]) {
        NSLog(@"Error creating %@: %@", databaseFolder, error);
    }
}

NSString *databasePath = [[databaseFolder stringByAppendingPathComponent:dbName] stringByAppendingPathExtension:@"db"];

if (![filemgr fileExistsAtPath:databasePath]) {
    // database creation logic
}