I am trying to retrieve a query from the Parse database; however, when I run the app and click the button to go to the view controller that is going to retrieve the data from the database, my app crashes. When the app crashes, I get sent the AppDelegate.swift file.
This is the error: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Method not allowed when Pinning is enabled.'
I made sure to implemented Parse correctly in my project. Also, when I take out the if self.objects.count == 0 {} code block, the app runs fine when I go to the view controller that is retrieving the data from the database. But only this time, there are no objects in my tableview list when there are objects in my parse database. Thanks in advance.
override func queryForTable() -> PFQuery {
let query = PFUser.query()
if searchInProgress {
// We are looking for the string contents in the search bar to match the names in the parse username category.
query?.whereKey("username", containsString: searchString)
}
// From the objects aleady loaded...
if self.objects?.count == 0{
// If we have not already loaded the elements from our database, then it will use the elements that have already been downloaded when we have already run the app
query?.cachePolicy = PFCachePolicy.CacheThenNetwork
}
query?.orderByAscending("username")
return query!
}
You can't use pinning and cache policy at the same time, hence the inconsistency exception.
http://parse.com/docs/ios/api/Classes/PFQuery.html#//api/name/cachePolicy
Related
I'm creating a signup form with multiple view controllers as "pages" and I need the information from one view controller such as 'First name' and 'last name' or 'email address' to another view controller. I decided I'm going to use core data to save the strings and retrieve them from another view controller rather than create a global struct for every view controller (because it crashes every time I try and implement it). Heres my code:
#IBAction func nextBtnWasPressed(_ sender: Any) {
if firstNameText.text != "" && lastNameText.text != "" {
//Core Data User Information
var userInfo = UserInfo() // The Name of the Core Data Entity
var firstName: String = firstNameText.text!
userInfo.firstName = firstName
do {
try NSManagedObjectContext.save(firstName)//Need Fixing
} catch {
fatalError("Failure to save context: \(error)")
}
performSegue(withIdentifier: "toBirthdate", sender: self)
} else {
nextBtn.alpha = 0.5
}
}
Here is the error log : 'Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UserInfo setFirstName:]: unrecognized selector sent to instance 0x600001530e80'
Full error log: View Here
Well, at first I was going to give the obvious answer which is that, in your Core Data data model, your UserInfo entity does not have a firstName attribute.
That's still possible, but then I looked at the full transcript you posted and saw that, a couple hundred microseconds before this error is another error:
Failed to call designated initializer on NSManagedObject class 'UserInfo'
I suspect this error indicates that you have initialized your managed object with init(). This is a common mistake of first-time Core Data users. Ensure that you are initializing your UserInfo object like this:
let userInfo = UserInfo.init(entity: entityDescription, insertInto: context);
or if your deployment target is iOS 10 or later, you can use the newer cleaner method:
let userInfo = UserInfo.init(context: context)
We have an app with a fairly broad Core Data model, with lots of custom subclasses implemented in Objective C, but which are also used by a growing fraction of the app that's written in Swift. (For what it's worth: we're building with Xcode 7.3.1 against iOS 9.3, and the Swift code is thus 2.2.)
There's a helper function written in Swift that looks like this:
extension NSManagedObject {
func inContext<T: NSManagedObject>(moc: NSManagedObjectContext) -> T? {
guard self.managedObjectContext != moc else {
return (self as! T)
}
do {
let obj = try moc.existingObjectWithID(self.objectID)
return (obj as! T) // <--- fails here
}
catch let error {
return nil
}
}
}
This is called in a fair number of places where objects jump contexts. Calling code generally looks like this:
let result: ECFoo? = foo.inContext(managedObjectContext)
This works flawlessly in debug builds of the app. But with optimizations turned on, I'm running into a case where this call fails at the line I've marked, where the fetched object is being cast from NSManagedObject to the correct subclass. The stack trace starts with swift_dynamicCastObjCClassUnconditional, and the message that gets logged to the console is:
Could not cast value of type 'ECFoo_Foo_' (0x7fb857d2c250) to 'ECFoo_Foo_' (0x7fb857d2c250).
If I put a breakpoint on that line, what I'm attempting to do seems fine in the debugger console:
(lldb) po moc.existingObjectWithID(self.objectID) is ECFoo
true
This is deeply confusing, because it's clearly the same type on both sides here, and they both appear to be the dynamically generated subclass, rather than the formal class that it should be trying to cast to (based on inference of the calling code). I can only assume that there's some piece of information being optimized away that is necessary to make this work, but I'm not entirely sure how to fix it.
App runs fine first time the simulator, but once new data is saved to Core Data the app will not launch again - crashing before the first view loads with an uncaught exception 'NSInternalInconsistencyException', reason: 'statement is still active'. There are 75 lines of pre-crash actions in the console, but nothing stands out (to my unskilled eyes).
If deleted, the app can be launched repeatedly until new data is saved to Core Data. After saving new data, it does not help to simply stop running the app or quit the simulator, it still crashes during launch.
Stackoverflow and the apple doc.s consistently suggest that it has something to do with threading, but my code is a bit simple for that - everything is on the main thread. I'd love to find things to try in swift or a swift process to identify the cause / solution.
I'm using the default xcode 7 Core Data stack in the AppDelegate class. Sample data is initially loaded into Core Data in one method, and then successfully loaded from core data. After saving a new record, (not re-launching) newly added data is successfully loaded from Core Data. The problem only occurs on re-launch.
In code, when a new record view controller is instantiated, I instantiate two managed objects with separate entities in a prepareForSegue method:
if segue.identifier == "newRecord"
{
let controller = (segue.destinationViewController as! NewRecordVC)
let appDelegate = UIApplication.sharedApplication().delegate as? AppDelegate // instantiate the delegate methods in AppDelegate
controller.managedContext = appDelegate!.managedObjectContext // create context from delegate methods
let recordEntity = NSEntityDescription.entityForName("RecordData", inManagedObjectContext: controller.managedContext)
let locationEntity = NSEntityDescription.entityForName("Location", inManagedObjectContext: controller.managedContext)
controller.location = Location(entity: locationEntity!, insertIntoManagedObjectContext: controller.managedContext)
controller.record = Record(entity: recordEntity!, insertIntoManagedObjectContext: controller.managedContext)
print("segueing")
}
In the new record view controller, managed object property values are defined, and the managed context is saved while unwinding.
if (segue.identifier == "UnwindSegue")
{
updateRecord() // managed object properties updated
do
{
try managedContext.save() // commit changes / save context
}
catch
{
print("There is some error.") // if error
}
}
When the app returns to the master view, the new record is fetched from Core Data and displayed on a table.
BUT when I relaunch the app - sadness.
I've learnt that when something is "discouraged" by apple, it's best to stay away from it.
Changing the override init in the subclass to awakeFromInsert fixed it, as per doc.s. Thanks Markus S. Zarra.
I'll make it short as possible.
I have an API request that I fetch data from (i.e. Parse).
When I'm getting the results I'm writing it to Realm and then adding them to a UICollectionView's data source.
There are requests that take a bit more time, which run asynchronous. I'm getting the needed results after the data source and collection view was already reloaded.
I'm writing the needed update from the results to my Realm database.
I have read that it's possible to use Realm's Results. But I honestly didn't understood it. I guess there is a dynamic and safe way working with collection views and Realm. Here is my approach for now.
This is how I populate the collection view's data source at the moment:
Declaration
var dataSource = [Realm_item]()
where Realm_item is a Realm Object type.
Looping and Writing
override func viewDidLoad() {
super.viewDidLoad()
for nowResult in FetchedResultsFromAPI
{
let item = Realm_item()
item.item_Title = nowResult["Title"] as! String
item.item_Price = nowResult["Price"] as! String
// Example - Will write it later after the collectionView Done - Async request
GetFileFromImageAndThanWriteRealm(x.image)
// Example - Will write it later after the collectionView Done - Async request
dataSource.append(item)
}
//After finish running over the results *Before writing the image data*
try! self.realm.write {
self.realm.add(self.dataSource)
}
myCollectionView.reloadData()
}
After I write the image to Realm to an already created "object". Will the same Realm Object (with the same primary key) automatically update over in the data source?
What is the right way to update the object from the data source after I wrote the update to same object from the Realm DB?
Update
Model class
class Realm_item: Object {
dynamic var item_ID : String!
dynamic var item_Title : String!
dynamic var item_Price : String!
dynamic var imgPath : String?
override class func primaryKey() -> String {
return "item_ID"
}
}
First I'm checking whether the "object id" exists in the Realm. If it does, I fetch the object from Realm and append it to the data source. If it doesn't exist, I create a new Realm object, write it and than appending it.
Fetching the data from Parse
This happens in the viewDidLoad method and prepares the data source:
var query = PFQuery(className:"Realm_item")
query.limit = 100
query.findObjectsInBackgroundWithBlock { (respond, error) -> Void in
if error == nil
{
for x in respond!
{
if let FetchedItem = self.realm.objectForPrimaryKey(Realm_item.self, key: x.objectId!)
{
self.dataSource.append(FetchedItem)
}
else
{
let item = Realm_item()
item.item_ID = x.objectId
item.item_Title = x["Title"] as! String
item.item_Price = x["Price"] as! String
let file = x["Images"] as! PFFile
RealmHelper().getAndSaveImageFromPFFile(file, named: x.objectId!)
self.dataSource.append(item)
}
}
try! self.realm.write {
self.realm.add(self.dataSource)
}
self.myCollectionView.reloadData()
print(respond?.count)
}
}
Thank you!
You seem to have a few questions and problems here, so I'll do my best.
I suggest you use the Results type as your data source, something like:
var dataSource: Results<Realm_item>?
Then, in your viewDidLoad():
dataSource = realm.objects(Realm_item).
Be sure to use the relevant error checking before using dataSource. We use an optional Results<Realm_item> because the Realm object you're using it from needs to be initialised first. I.e., you'll get something like "Instance member * cannot be used on type *" if you try declaring the results like let dataSource = realm.objects(Realm_item).
The Realm documentation (a very well-written and useful reference to have when you're using Realm as beginner like myself), has this to say about Results...
Results are live, auto-updating views into the underlying data, which means results never have to be re-fetched. Modifying objects that affect the query will be reflected in the results immediately.
Your mileage may vary depending on how you have everything set up. You could try posting your Realm models and Parse-related code for review and comment.
Your last question:
What is the right way to update the "object" from the Data Source after i wrote the update to same object from the Realm DB?
I gather you're asking the best way to update your UI (CollectionView) when the underlying data has been updated? If so...
You can subscribe to Realm notifications to know when Realm data is updated, indicating when your app’s UI should be refreshed for example, without having to re-fetch your Results.
Before getting into my issue, please have a look at this image.
Here is the actual data model:
I retrieve a set of Records from a web API, create objects out of them, save them in core data and display them in the Today view. By default these records are returned for the current date.
The user can tap on Past button to go to a separate view where he can choose a past or future date from a date picker view and view Records for that selected date. This means I have to call the API again passing the selected date, retrieve the data and save that data in core data and display them. When the user leaves this view, this data should be discarded.
This is the important part. Even though I get a new set of data, the old original data for the current date in the Today view must not go away. So if/when the user returns to the Today view, that data should be readily available as he left it without the app having to call the API and get the data for the current date again.
I thought of creating a separate NSManagedObjectContext to hold these temporary data.
I have a separate class called DatabaseManager to handle core data related tasks. This class initializes with an instance of `NSManagedObjectContext. It creates the managed object classes in the given context.
import CoreData
import Foundation
import MagicalRecord
import SwiftyJSON
public class DatabaseManager {
private let context: NSManagedObjectContext!
init(context: NSManagedObjectContext) {
self.context = context
}
public func insertRecords(data: AnyObject, success: () -> Void, failure: (error: NSError?) -> Void) {
let json = JSON(data)
if let records = json.array {
for recordObj in records {
let record = Record.MR_createInContext(context) as Record
record.id = recordObj["Id"].int
record.name = recordObj["Name"].string!
record.date = NSDate(string: recordObj["Date"].string!)
}
context.MR_saveToPersistentStoreAndWait()
success()
}
}
}
So in the Today view I pass NSManagedObjectContext.MR_defaultContext() to insertRecords() method. I also have a method to fetch Records from the given context.
func fetchRecords(context: NSManagedObjectContext) -> [Record]? {
return Record.MR_findAllSortedBy("name", ascending: true, inContext: context) as? [Record]
}
The data is retrieved from the API, saved in core data and gets displayed successfully. All good so far.
In the Past View, I have to do basically the same thing. But since I don't want the original data to change. I tried to do this a few ways which MagicalRecord provides.
Attempt #1 - NSManagedObjectContext.MR_context()
I create a new context with NSManagedObjectContext.MR_context(). I change the date in Past view, the data for that selected date gets retrieved and saved in the database successfully. But here's the issue. When I fetch the objects from core data, I get that old data as well. For example, each day has only 10 records. In Today view I display 10 records. When the fetch objects in the Past view, I get 20 objects! I assume it's the old 10 objects plus the new ones. Also when I try to display them in the tableview, it crashes with a EXC_BAD_ACCESS error in the cellForRowAtIndexPath method.
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell
let record = records[indexPath.row]
cell.textLabel?.text = record.name // EXC_BAD_ACCESS
cell.detailTextLabel?.text = record.date.toString()
return cell
}
Attempt #2 - NSManagedObjectContext.MR_newMainQueueContext()
The app crashes when I change the date with the following error.
'+entityForName: nil is not a legal NSPersistentStoreCoordinator for searching for entity name 'Record''
Attempt #3 - NSManagedObjectContext.MR_contextWithParent(NSManagedObjectContext.MR_defaultContext())
Same result as Attempt #1.
Attempt #4 - From Hal's Answer I learned that even though I create two MOCs, they both refer to the same NSPersistentStore. So I created another new store to hold the temporary data in my AppDelegate.
MagicalRecord.setupCoreDataStackWithStoreNamed("Records")
MagicalRecord.setupCoreDataStackWithStoreNamed("Records-Temp")
Then when I change the date to get the new data, I set that temporary store as the default store like this.
func getDate(date: NSDate) {
let url = NSPersistentStore.MR_urlForStoreName("Records-Temp")
let store = NSPersistentStore(persistentStoreCoordinator: NSPersistentStoreCoordinator.MR_defaultStoreCoordinator(), configurationName: nil, URL: url, options: nil)
NSPersistentStore.MR_setDefaultPersistentStore(store)
let context = NSManagedObjectContext.MR_defaultContext()
viewModel.populateDatabase(date, context: context)
}
Note that I'm using the default context. I get the data but it's the same result as Attempt 1 and 3. I get 20 records. They include data from both the old date and the new date. If I use NSManagedObjectContext.MR_context(), it would simply crash like in Attempt 1.
I also discovered something else. After creating the stores in App Delegate, I printed out the default store name println(MagicalRecord.defaultStoreName()) in the Today's view. Strangely it didn't print the name I gave the store which is Records. Instead it showed Reports.sqlite. Reports being the project's name. Weird.
Why do I get the old data as well? Am I doing something with when initializing a new context?
Sorry if my question is a little confusing so I uploaded a demo project to my Dropbox. Hopefully that will help.
Any help is appreciated.
Thank you.
Thread Safety
First of all I want to mention the Golden Rule of Core Data. NSManagedObject's are not thread safe, hence, "Thou shalt not cross the streams" (WWDC). What this means is that you should always access a Managed Object in its context and never pass it outside of its context. This is why your importer class worries me, you are inserting a bunch of objects into a context without guaranteeing that you are running the insert inside the Context.
One simple code change would fix this:
public func insertRecords(data: AnyObject, success: () -> Void, failure: (error: NSError?) -> Void) {
let json = JSON(data)
context.performBlock { () -> Void in
//now we are thread safe :)
if let records = json.array {
for recordObj in records {
let record = Record.MR_createInContext(context) as Record
record.id = recordObj["Id"].int
record.name = recordObj["Name"].string!
record.date = NSDate(string: recordObj["Date"].string!)
}
context.MR_saveToPersistentStoreAndWait()
success()
}
}
}
The only time you don't need to worry about this is when you are using the Main Queue Context and accessing objects on the main thread, like in tableview's etc.
Don't forget that MagicalRecord also has convenient save utilities that create context's ripe for saving :
MagicalRecord.saveWithBlock { (context) -> Void in
//save me baby
}
Displaying Old Records
Now to your problem, the following paragraph in your post concerns me:
The user can tap on Past button to go to a separate view where he can
choose a past or future date from a date picker view and view Records
for that selected date. This means I have to call the API again
passing the selected date, retrieve the data and save that data in
core data and display them. When the user leaves this view, this data
should be discarded.
I don't like the idea that you are discarding the information the user has requested once they leave that view. As a user I would expect to be able to navigate back to the old list and see the results I just queried without another unecessary network request. It might make more sense to maybe have a deletion utility that prunes your old objects on startup rather than while the user is accessing them.
Anyways, I cannot illustrate how important it is that you familiarize yourself with NSFetchedResultsController
This class is intended to efficiently manage the results returned from
a Core Data fetch request.
You configure an instance of this class using a fetch request that
specifies the entity, optionally a filter predicate, and an array
containing at least one sort ordering. When you execute the fetch, the
instance efficiently collects information about the results without
the need to bring all the result objects into memory at the same time.
As you access the results, objects are automatically faulted into
memory in batches to match likely access patterns, and objects from
previous accessed disposed of. This behavior further serves to keep
memory requirements low, so even if you traverse a collection
containing tens of thousands of objects, you should never have more
than tens of them in memory at the same time.
Taken from Apple
It literally does everything for you and should be your go-to for any list that shows objects from Core Data.
When I fetch the objects from core data, I get that old data as well
Thats to be expected, you haven't specified anywhere that your fetch should include the reports in a certain date range. Here's a sample fetch:
let fetch = Record.MR_createFetchRequest()
let maxDateForThisController = NSDate()//get your date
fetch.predicate = NSPredicate(format: "date < %#", argumentArray: [maxDateForThisController])
fetch.fetchBatchSize = 10// or an arbitrary number
let dateSortDescriptor = NSSortDescriptor(key: "date", ascending: false)
let nameSortDescriptor = NSSortDescriptor(key: "name", ascending: true)
fetch.sortDescriptors = [dateSortDescriptor,nameSortDescriptor]//the order in which they are placed in the array matters
let controller = NSFetchedResultsController(fetchRequest: fetch,
managedObjectContext: NSManagedObjectContext.MR_defaultContext(),
sectionNameKeyPath: nil, cacheName: nil)
Importing Discardable Records
Finally, you say that you want to see old reports and use a separate context that won't save to the persistent store. Thats also simple, your importer takes a context so all you would need to do is make sure that your importer can support imports without saving to the persistent store. That way you can discard the context and the objects will go with it. So your method signature could look like this:
public func insertRecords(data: AnyObject, canSaveToPersistentStore: Bool = true,success: () -> Void, failure: (error: NSError?) -> Void) {
/**
Import some stuff
*/
if canSaveToPersistentStore {
context.MR_saveToPersistentStoreWithCompletion({ (complete, error) -> Void in
if complete {
success()
} else {
error
}
})
} else {
success()
}
}
The old data that was in your persistent store, and addressed with the original MOC, is still there, and will be retrieved when the second MOC does a fetch. They're both looking at the same persistent store. It's just that the second MOC also has new data fetched from your API.
A synchronous network operation saving to Core Data will hang your app, and (for a large enough set of records) cause the system to kill your app, appearing to the user as a crash. Your client is wrong on that point, and needs to be educated.
Break apart your logic for fetching, saving, and viewing. Your view that shows a particular date's records should just do that--which it can do, if it accepts a date and uses a predicate.
Your 'cellForRowAtIndexPath' crash smells like a problem with a missing or misspelled identifier. What happens if you hard code a string instead of using 'record.name'?