PFUser currentUser saveInBackgroundWithBlock completes succeeded without even trying

Question

I am trying to alter the logged in user. I make my changes as usual, and I call:

[[PFUser currentUser] saveInBackgroundWithBlock:^(BOOL succeeded, NSError *PF_NULLABLE_S error){
    if(succeeded){
        NSLog(@"Saved user successfully.");
    }else{
        NSLog(@"Unable to save user: %@", error);
    }
}];

It saves successfully, but my changes are gone. Just before saving, my user objects has this key:

.meta.acceptsAllMessages = 1. The moment save completion block returns, that key is gone. `(meta is my generic JSON object at user, and other values in meta key are retained with no problem). My changes aren't also reflect to the server side too.

The first suspect was the beforeSave trigger, however there's absolutely nothing related to meta keys in my trigger, so that's not the case. Why would this happen?

UPDATE: There seems to be a problem deeper down. I was saving something else entirely, and ran into the same issue. I've enabled airplane mode, and I wanted to save my current user, and it called the completion handler immediately, with succeeded set to YES and error set to nil without an internet connection. I've double checked that I'm using saveInBackgroundWithBlock: and not saveEventually. Why does this happen?

Answer 1

Okay, I've found the solution. I was adding an object to the array inside my user object, without assigning the property itself. In the latest instance, I was doing something like:

[[PFUser currentUser][@"myArray"] addObject:@"something"];
[[PFUser currentUser] saveInBackground...];

Because I was not assigning any object itself, [my assumption is that] Parse thought that my user object was not dirty, and it completed immediately without even trying to save. I've solved the problem like this:

NSMutableArray *array = [PFUser currentUser][@"myArray"];
[array addObject:@"something"];
[PFUser currentUser][@"myArray"] = array;

The last line is the key. I'm assigning to the "myArray" field of Parse object, which causes Parse to mark my user dirty. Then, when I save, because it is dirty, it actually saves my user to the server, and it works.