我刚开始使用 iPhone 核心数据,在轻量级迁移中遇到了问题。
- 我在旧模型中添加了两个新字段
- 重新生成模型类文件
- 将新模型版本作为当前版本
在生成的模板中的 AppDelegate 中添加以下代码
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
if (![persistentStoreCoordinator_addPersistentStoreWithType:NSSQLiteStoreType 配置:nil URL:storeURL 选项:选项错误:&error]) {
最后,我在运行应用程序之前做了一个干净的构建。
当应用程序崩溃时,我收到以下错误...
The operation couldn’t be completed. (Cocoa error 134140.)" UserInfo=0x622b350 {reason=Can't find or automatically infer mapping model for migration
现在要调试,我添加了以下代码...
NSError *error = nil;
NSDictionary *sourceMetadata = [NSPersistentStoreCoordinator metadataForPersistentStoreOfType:NSSQLiteStoreType URL:storeURL error:&error];
if (!sourceMetadata) {
NSLog(@"sourceMetadata is nil");
} else {
NSLog(@"sourceMetadata is %@", sourceMetadata);
}
这将显示以下结果...
2011-01-20 18:18:41.018 MyApp[4438:207] sourceMetadata is {
NSPersistenceFrameworkVersion = 248;
NSStoreModelVersionHashes = {
Fugitive = <e33370b6 e7ca3101 f91d2595 1e8bfe01 3e7fb4de 6ef2a31d 9e50237b b313d390>;
};
NSStoreModelVersionHashesVersion = 3;
NSStoreModelVersionIdentifiers = (
);
NSStoreType = SQLite;
NSStoreUUID = "E711F65F-3C5A-4889-872B-6541E4B2863A";
"_NSAutoVacuumLevel" = 2;
}
我检查了应用程序包 > MyApp.momd > VersionInfo.plist 文件
它有以下内容......
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>NSManagedObjectModel_CurrentVersionName</key>
<string>MyApp 2</string>
<key>NSManagedObjectModel_VersionHashes</key>
<dict>
<key>MyApp</key>
<dict>
<key>Fugitive</key>
<data>
4zNwtufKMQH5HSWVHov+AT5/tN5u8qMdnlAje7MT05A=
</data>
</dict>
<key>MyApp 2</key>
<dict>
<key>Fugitive</key>
<data>
N58Lf4BNpACzrsHAb1+BQImgjsBZ+u5G0wGUyt84+Ec=
</data>
</dict>
</dict>
</dict>
</plist>
我在这里想念什么?
更新:问题原来是我在模型中错过的默认值属性。