iOS，CoreData，SQLite，文件丢失数据 [英] iOS, CoreData, SQLite, File losing its data
问题描述
我有一个应用程序，它通过从json文件导入到sqlitedb中来生成一些静态数据，当运行该应用程序时，数据库文件中包含数据并且已正确加载，我通常会进入通常位于
I have an app that generates some static data by importing from a json file into a sqlitedb, When running the app the DB file has data in it and is loaded properly, I usually go to the build folder "usually under
/Library/Application Support/iPhone Simulator/7.0.3-64/Applications/
并检查sqlite文件并验证它是否有数据
现在我复制相同的文件夹并将其粘贴到桌面上，然后打开
我注意到在每个sqlite文件中都会生成一个-shm和-wal文件。
and inspect the sqlite file and verify that it does have data. Now I copy that same folder and paste it on the desktop, and open it in the same sqlite browser, and the data is gone?? why I don't know!! I notice that for every sqlite file there is a -shm and -wal file generated.
为什么会这样？
好，所以我尝试了一些调查，我有两种情况：
Ok so I tried a little bit more investigating, I have two scenarios :
1：我在完成生成SQLite文件后立即放置一个断点，然后转到build文件夹。如果我将该文件复制到台式机数据库丢失了数据。
1 : I put a break point right after I finished generating the SQLite file, and then go the build folder, In the build folder the DB has data in it, if I copy that file to the desktop the db loses its data.
2：我不放置断点，让应用正常完成（正常运行），然后转到build文件夹，db文件包含数据，当我将其复制并粘贴到在桌面上，它仍然保留数据。
2 : I don;t put a break point, let the app finish normally ( gracefully ) and then go to the build folder, the db file has data, and when I copy and paste it to the desktop it still retains the data.
所以我认为当xcode退出（或者应用程序正常关闭）时，发生了某些事情，当我放置断点时，我就错过了!!
So I assume there's something that happens when xcode exits ( or the app closes normally ) that I am missing out on when I put a breakpoint !!
推荐答案
从iOS 7开始，默认情况下在 Journaling 模式下使用sqlite数据库-这意味着对数据库的所有更改被写入更新文件，而不是直接写入数据库。您可以将行为改回旧方式-在此处查看完整说明
：
Starting with iOS 7 the sqlite database is used in Journaling mode by default - which means that all changes to the database are written to "update files", not to the database directly. You can change the behaviour back to the "old" way - have a look here for a complete explanation :
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