将 NSDATA 检索到 NSDictionary 时出现 NSCocoaErrorDomain Code=3840 问题

问题描述

我正在创建使用 SQLite DB 的 iOS 应用程序.我已经创建了表为:

I am creating iOS app which uses SQLite DB.I have created Table As:

const char *sql_stmt = "CREATE TABLE IF NOT EXISTS ORDERTABLE (ID INTEGER PRIMARY KEY AUTOINCREMENT, ITEMDESC BLOB)";

然后我必须将 self.selectedItemsDictnory Dictionary 插入到 ItemDESC我插入为:

and then I have to insert self.selectedItemsDictnory Dictionary into ItemDESCi am inserting as :

NSData *data = [NSJSONSerialization dataWithJSONObject:self.selectedItemsDictnory options:NSJSONWritingPrettyPrinted error:nil];

NSString *insertSQL = [NSString stringWithFormat: @"INSERT INTO ORDERTABLE(ITEMDESC)VALUES( \"%@\");",data];

到此就成功了.

现在我必须以相同的格式检索这本字典

Now i have to retrieve this dictionary in same format

我正在做的是:

if (sqlite3_prepare_v2(orderDB, sqlStatement, -1, &statement, NULL) == SQLITE_OK) {

    while (sqlite3_step(statement) == SQLITE_ROW) {
        int uniqueId = sqlite3_column_int(statement, 0);

        const void *blob = sqlite3_column_blob(statement, 1);
        NSInteger bytes = sqlite3_column_bytes(statement, 1);
        NSData *data = [NSData dataWithBytes:blob length:bytes];
        NSError *error;

        NSMutableString *jsonObject=[NSJSONSerialization
                                         JSONObjectWithData:data
                                         options:NSJSONReadingMutableLeaves
                                         error:&error];
        NSLog(@"jsonObject is %@ with error %@",jsonObject, error);

    }

    sqlite3_finalize(statement);
    sqlite3_close(orderDB);
}

我收到错误

Error Domain=NSCocoaErrorDomain Code=3840 "操作不能完全的.(Cocoa 错误 3840.)"(JSON 文本未以数组或允许未设置片段的对象和选项.)

推荐答案

您没有设置 JSON 属性的格式.在此:

You are not formatting the JSON property. In this:

NSData *data = [NSJSONSerialization dataWithJSONObject:self.selectedItemsDictnory options:NSJSONWritingPrettyPrinted error:nil];

现在你有一个数据 blob，不是一个字符串，但在下面，你把它当作一个字符串:

Now you have a data blob, not a string, but below, you treat it as a string:

NSString *insertSQL = [NSString stringWithFormat: @"INSERT INTO ORDERTABLE(ITEMDESC)VALUES( \"%@\");",data];

如果你想要一个字符串:

If you want a string:

NSString *jsonString = [NSString alloc] initWithData:data encoding: NSUTF8StringEncoding];
NSString *insertSQL = [NSString stringWithFormat: @"INSERT INTO ORDERTABLE(ITEMDESC)VALUES( \"%@\");",jsonString];

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