Question

我正在尝试更新一行中的一个单元格，但我无法正常工作。更新方法：

- (void) UpdateQuestionShownParameter:(int)QuestionId :(BOOL)QuestionShown{
    @try {
        NSFileManager *fileMgr = [NSFileManager defaultManager];
        NSString *dbPath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"Milionar.sqlite"];
        const char *sql = "UPDATE Questions set Show = ? WHERE id = ?";


        BOOL success = [fileMgr fileExistsAtPath:dbPath];
        if(!success)
        {
            NSLog(@"Cannot locate database file '%@'.", dbPath);
        }
        if(sqlite3_open([dbPath UTF8String], &db) == SQLITE_OK)
        {
            sqlite3_stmt *sqlStatement;
            if(sqlite3_prepare_v2(db, sql, -1, &sqlStatement, NULL) == SQLITE_OK)
            {
                NSInteger shownInteger = (QuestionShown ? 1 : 0);

                sqlite3_bind_int(sqlStatement, 1, shownInteger);
                sqlite3_bind_int(sqlStatement, 2, QuestionId);

                if (sqlite3_step(sqlStatement) != SQLITE_DONE)
                {
                    NSLog(@"Error while updating. '%s'", sqlite3_errmsg(db));
                }
                sqlite3_finalize(sqlStatement);

            }
            else
            {
                NSLog(@"Problem with prepare statement");
            }
        }
        else
        {
            NSLog(@"An error has occured while opening database.");
        }

        sqlite3_close(db);

    }
    @catch (NSException *exception) {
        NSLog(@"An exception occured: %@", [exception reason]);
    }
}

在ViewDidLoad中尝试：

- (void)viewDidLoad
{
    ListOfQuestions *listQuestions =[[ListOfQuestions alloc] init];
    self.Questions = [listQuestions getQuestions];
    Question *generatedQuestion = (Question *) [self.Questions objectAtIndex:0];
    [listQuestions UpdateQuestionShownParameter:generatedQuestion.id :TRUE];
    [self.Description setText:(generatedQuestion.Description)];

    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

每当我试图运行应用程序时，我会在显示的列中得到0。但我没有任何错误。所以，我做错了什么或每当我试图在模拟器中运行应用程序时，我从项目数据库中重新创建数据库？感谢

Answer 1

您正在打开捆绑包中的数据库，该数据库是只读的。如果数据库尚不存在于Documents文件夹中，您应该将数据库从bundle复制到Documents文件夹：

NSString *filename         = @"Milionar.sqlite";
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *bundlePath       = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:filename];
NSString *documentsFolder  = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *documentsPath    = [documentsFolder stringByAppendingPathComponent:filename];

if (![fileManager fileExistsAtPath:documentsPath]) {
    NSError *error = nil;
    BOOL success = [fileManager copyItemAtPath:bundlePath toPath:documentsPath error:&error];
    NSAssert(success, @"Unable to copy database: %@", error);
}

if (sqlite3_open([documentsPath UTF8String], &db) != SQLITE_OK) {
    NSLog(@"Open failed");
} else {
    // ...
}

有关文档所属位置的详细信息，请参阅File System Programming Guide。

顺便说一下，如果您正在寻找模拟器的Documents文件夹，那么它位于~/Library/Application Support/iPhone Simulator（在Xcode 6中，现在是~/Library/Developer/CoreSimulator/Devices）。如果您没有看到“Library”文件夹，可以通过在终端命令行界面中键入以下命令来取消隐藏它：

chflags nohidden ~/Library

更新sqlite中的更新行

1 个答案: