I am a pretty knowledgable iOS dev and I feel stupid for not being able to figure this out. I am currently working on a new app that upon launch checks for the last user, sets this property on the AppDelegate as well as the users's company property. These items are stored in Core Data. On the AppDelegate I have overridden the setter for the Company property to make a network request as I need to perform a fetch every time this is set. The request goes through fine but when the call comes back (Im using AFNetworking 2) and I begin to parse the info and perform some actions on it, the responseObject is nil'd out. I feel like this should be pretty obvious but I cannot figure it out. Any help would be appreciated. I have tried to assign the response to a new property and variable, with and without copying the actual object.
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Hi fellow iOS developers, I have seem to run into a roadblock here with coredata and Im fairly certain this is should be a common use case. But I am either not querying google correctly or my design with handling managed objects was bad which led to this problem.
So basically, the problem that I am facing is the following..
User creates a new managed object object.
User updates said new managed object object (say edit the name
field)
** The following is the problem **
User wants to edit the same field again, but decides to discard their changes
What is the right thing to do here? Initially I was using .refresh() on the managed object context, but that only works if the object is persisted in the database.
Essentially, I don't want to save the object until the user explicitly opts to "save". Which leaves me in this limbo land. At first one of my thoughts was to created regular objects and convert them into core data objects when "save" is selected. However, that proved to be inefficient especially when handling multiple relationships.
I would think that there is something that is provided that aims to solve this problem, im just not quite querying google correctly.
I am writing an iOS app with Swift using Parse.
In my User table, I have a pointer field called UserAddress which is pointing to an Address table record. I would like to pull this Address data for current user. I did a bit of research and figured out fetching in background is an option but I would like to avoid it. Is there an alternative to pull this data without running extra fetch work?
What I can imagine is:
Fetching pointer data in AppDelegate before the app gets ready to use for users.
Somehow, force to set includeKey when loading a currentUser
Any of the above is feasible? Please advise me.
You correctly understand the two options, and they are the only two options. For non-user objects, usually includeKey() on a query is the way to go.
For the current user, since you have the user already, it would seem a little strange to query the user, including the pointer, just to avoid fetching the pointer, but that would work. You might be better off working on whatever's making you hesitant to do the fetch().
Using Parse for iOS, I modified the _User's table to have a field called "Friends" which is an array of pointers to other _Users (by the way, I also have other additional fields).
When I call PFUser.currentUser(), I don't see this friends field in the user object. So I call PFUser.currentUser().fetch() (because refresh method doesn't seem to exist anymore) and I finally have the friends field in my currentUser object.
However, as soon as I exit the app, this field is lost. It doesn't seem to be saved locally unlike all the other fields of the current user.
How am I supposed to force a refresh of the cached current user ?
According to parse.com itself and one of their posts, there is no other way to keep your user up-to-date:
saveEventually does not write through any caches at this time,
including the currentUser, if the app has been restarted. You'll need
to regularly call fetch to keep it up-to-date. We are aware that this
is inconvenient, and are looking into ways to make it work better for
you.
Are you sure that you want your user objects to contain a value that's an array like that? I obviously don't know your use application, but I would recommend using a PFRelation instead. It works just like an array, but the Parse Framework provides a bunch of additional functionality along with it.
As for your specific question it might have to deal with Parse. Maybe they don't automatically retrieve and save arrays that are on an object. That would be my guess because an array could contain who knows how much data in it. I still don't know why they wouldn't locally save that data after it's fetched.
My suggestion is probably a little over the top, but would most likely be the best outcome. Utilize a local database such as CoreData or even the ParseLocalDatastore. Then encapsulate the Parse framework to have your own User object where you can store the information, which can also maintain persistence via your database.
This is a bit of a crazy one. I have an IOS app that saves an object to Parse.com's datastore. Until a couple of days ago everything worked well. Now, suddenly, the object is not going into the database. I would put the code here but it doesn't seem to be the issue, as it gets even more bizarre:
When I go directly to the data browser and insert a row manually, it shows up right there.
But when I refresh the data browser -- the object is gone.
Looking at the forums here's some more data:
When I save from the app, I have an existing current user.
The object itself exists.
The permissions on my class are all "Public."
The app codes are correct (I'm able to read from the database.)
I'm even seeing the saveInTheBackground success block getting called, and printing out the object it has a valid object id!!!
But then it goes pooooooffff and is gone.
Any idea what's happening?
EDIT: I added a different class with the exact same columns, changed the appropriate fields in the app, and now everything works. But this is obviously alarming, that a class stops saving objects all of a sudden. Any idea why?
I have an application that I'm writing that pulls data from a few network sources:
1) list of blog posts (UITableViewController)
2) list of videos (UIViewController with an embedded UIScrollView)
3) list of images (UIViewController with an embedded UIScrollView)
Right now, there is a home screen with a menu and when you push one of the buttons, a destinationViewController (described above) is what loads the data on demand. I've noticed this is quite slow, especially when on a cellular data connection as opposed to wifi.
I was thinking about creating a class that requests all the data up front and kick it off every time the app is reentered. Does anyone have suggestions that could help me answer the following?
1) are there any classes, frameworks, or existing i code i can use to kick off these requests in a single place?
2) how do my destination view controllers (mentioned above) get the data?
3) how do my destination view controllers get informed that the data is ready if they happen to be invoked before the data is available?
4) is there a better strategy i should employ?
I appreciate the help.
Thanks,
jas
Off the top of my head, I would make the request class you mentioned and start all the request methods in applicationDidFinishLaunching in AppDelegate. I would also probably make custom NSObjects for each type of object you would be fetching and in each of your request class methods, convert the fetched data into said object, then cache each object to disk as they are downloaded. Then in your viewcontrollers, fetch the cached objects as needed.
When you are cacheing, make sure you cache each object with a key that will 100% be unique, because you are going to want to run a check on the current local cache before you start a new download. I would probably string together the file type and file name, and set that string as the key for the cached object.
To run the check on current cache in your request class methods, something that says "if current cache contains object for key:
uniqueKey... do nothing. If else, start the download and cache the object when finished."
Also run a check in your view controllers, because you're also going to want to handle the case where your view controller is requesting a cached object, but it hasn't downloaded yet. So something along the lines of "if current cache has object for key:key, great! use it. If else, start the download... cache it... then give me a call back here so i can use it while I display a loading message to the end user."
Im sure there are other scenarios that you are going to have to deal with, but that's the theoretical direction I would head in.
EDIT:
check out this, it will probably help you a lot. I think it also uses Ego Cache (if you dont want to write your own cache methods): https://github.com/Infusion-apps/Download-Manager
EDIT 2:
I also agree with #RyanDignards point #4. If possible, avoid fetching data you don't need. However, only you really know your UI/UX and app functionality, and my suggestion is assuming there is a good chance your end user is going to be using your app for the sole purpose of consuming the content you provide. So they are most likely going to be wanting to read the blog posts, watch the videos etc... The call is up to you, if you think there is more of a chance that the user will be viewing all the content than not, I would go the preload route, because nothing pisses off a user like having to wait.
1) RestKit is generally regarded as one of the the standard web interaction frameworks http://restkit.org
2) RestKit provides methods such as -[getObjectsAtPath: parameters: success: failure:] or post, which will provide the response in success. Additionally, it can convert the response directly into the respective objects for you with mapping.
3) Generally I would post a notification which is unique to that request, and any controller interested would get notified, with the response located on notification.object within the listener. Additionally most network requests provide for a callback handler where you could update the UI directly.
4) I would advise against preemptive loading since you're using resources for something that you may not actually use. My advice would be to breakdown your calls to the smallest possible level, then as the notifications are posted, that data would be inserted into the UI.