我想重新创建(删除和创建)persistentStore不受更改.xcdatamodeld的影响.
我在AppDelegate中编写了一个代码persistentStoreCoordinator,如下所示:
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"myproject.sqlite"];
// delete if database exists
NSError *error = nil;
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
// if .xcdatamodeld is changed, fail and in here...
// if not changed, recreate success. all data removed from database
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
NSArray *stores = [_persistentStoreCoordinator persistentStores];
for (NSPersistentStore *store in stores) {
[_persistentStoreCoordinator removePersistentStore:store error:nil];
[[NSFileManager defaultManager] removeItemAtPath:store.URL.path error:nil];
}
// newly create database
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
当我对.xcdatamodeld进行更改(例如,向实体添加新列)和重新启动模拟器时,首先失败的是addPersistentStoreWithType并且log表示
Unresolved error Error Domain=NSCocoaErrorDomain Code=134100
The operation couldn’t be completed. (Cocoa error 134100.)
我怎样才能做到这一点?
最佳答案 以下代码对我来说似乎很有用.
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"myproject.sqlite"];
// delete database if exists
[[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:nil];
// create database
NSError *error = nil;
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
我在下面检查过(在设备和模拟器中):
>首次启动时,应创建数据库
>编辑.xcdatamodeld(添加/编辑/删除列或实体)然后重新启动,应重新创建数据库
谢谢你的建议.