问题
How do I find the replacement method in MagicalRecord for this (which has been deprecated)? I have looked at Google, SO and the docs; nothing seems to be a replacement, and of course, nothing in the docs tell you what replaced the deprecated method. :-{
[[NSManagedObjectContext MR_contextForCurrentThread] MR_saveErrorHandler:^(NSError *error)
回答1:
The deprecated method in question is:
[NSManagedObjectContext MR_contextForCurrentThread]
I did write a little blog post about this a while ago, though I admit it is on my personal blog, and not in any official docs. But, TL;DR, the bottom line is, in the world of GCD and queues, you cannot guarantee a 1-1 mapping of a queue to a thread, despite GCD being run on threads. The way to make sure things work going forward for you is using the following pattern:
[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) {
//make your changes in the localContext
}];
This solves the subtle cross thread issues that crop up in contextForCurrentThread by simply enforcing the rule that you should do all work in a different thread in a thread specific context. By creating a new context every time you save, and not re-using the context, you will guarantee to not cross threads, and to not crash your app 1% of the time.
回答2:
casademora is correct but I'll try to be more precise because I encounter some issues when converting my
[[NSManagedObjectContext MR_contextForCurrentThread] MR_saveToPersistentStoreWithCompletion:nil];
into
[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext)
You have to be careful to change or create your entities inside the block but it's not enough.
To retrieve your entities you must use selection request with context too.
MR_findFirstByAttribute:withValue
is not enough and updates won't be saved. You have to use instead
MR_findFirstByAttribute:withValue:InContext:localContext
And when creating entity, it's the same
MR_createEntity
must be change to
MR_createEntityInContext:localContext
Then it works like a charm :)
来源：https://stackoverflow.com/questions/20535419/what-is-the-replacement-method-for-this-magicalrecord-deprecated-call