UI Freeze with Magical Record

Question

Hello I am Riccardo and I am an indie developer!

it's not a lot that I have been starting programming in objective-c, and I am still a novice! :D

I started to learn Core Data and everything was going fine until I faced concurrency! With Core Data my app was continuing to block during save actions, so I googled for core data with background context and I found Magical Record.

With Magical Record I have drastically reduced the complexity of my code :) But I have still one problem, I read everything about Magical Record, I tried to fix it using different methods but the UI freeze is still there :( so I don't know how to fix it...

Although I think there are problem in all method (looking at freeze UI) 3 of the 4 methods listed are really fast so it is not perceptible. The only method that as huge problem and you can actually notice a freeze is this one -->

• (void) persistAppsFromArray: (NSArray *) arrayOfApps inResearch: (NSDictionary *) info;

Where I take an array in order to create all the apps objects and after I associate (after a fetch to find the research, I use the dictionary to create predicates) these apps to the research.

This is my code. It is actually a whole class that manage core data stuff. I don't use queues or threads in the class that call these methods, so I think there is something to fix here :-/

I thank you in advance :)

#import "CoreDataHelper.h"
#import "CoreData+MagicalRecord.h"


@implementation CoreDataHelper

#pragma mark - Research creator helper

+ (ResearchType *) fetchResearchWithDictionary: (NSDictionary *) info {

// Fetch
// predicates for fetch
NSPredicate * predicateCategory = [NSPredicate predicateWithFormat:@"researchCategory = %@" , [info objectForKey: @"Category"]];
NSPredicate * predicateType = [NSPredicate predicateWithFormat:@"researchType = %@" , [info objectForKey: @"Type"]];
 NSPredicate * predicatePrefix = [NSPredicate predicateWithFormat:@"researchPrefix = %@" , [info objectForKey: @"Prefix"]];

 NSArray * predicates = [NSArray arrayWithObjects: predicateCategory, predicateType, predicatePrefix, nil];

        // create the composite predicate
        NSPredicate * predicateComposito = [NSCompoundPredicate andPredicateWithSubpredicates:predicates];

    // obtain the result
    // Passo la ricerca al brain
   return [ResearchType MR_findFirstWithPredicate: predicateComposito];
}

---

   + (void)updateResearchWithDictionary:(NSDictionary *) info withCompletionBlock:(completion_block)updatedResearch {

    // Get the context
    NSManagedObjectContext *localContext    = [NSManagedObjectContext MR_context];

    // predicates
    NSPredicate * predicateCategory = [NSPredicate predicateWithFormat:@"researchCategory = %@" , [info objectForKey: @"Category"]];
    NSPredicate * predicateType = [NSPredicate predicateWithFormat:@"researchType = %@" , [info objectForKey: @"Type"]];
    NSPredicate * predicatePrefix = [NSPredicate predicateWithFormat:@"researchPrefix = %@" , [info objectForKey: @"Prefix"]];

    NSArray * predicates = [NSArray arrayWithObjects: predicateCategory, predicateType, predicatePrefix, nil];

    // composite predicate
    NSPredicate * predicateComposito = [NSCompoundPredicate andPredicateWithSubpredicates:predicates];

// create research object 
    ResearchType *research = [ResearchType MR_findFirstWithPredicate: predicateComposito inContext:localContext];



// new properties
    research.researchDate      = [info objectForKey:@"Research Date"];
    research.researchLimit     = [info objectForKey:@"Limit"];
    //research.apps              =  nil;

  [localContext MR_saveInBackgroundCompletion:^{

      updatedResearch(research);

  }];
 }

---

   + (void) persistResearchWithDictionary: (NSDictionary *) info withCompletionBlock:(completion_block)savedResearch {

// Get the context
NSManagedObjectContext *localContext    = [NSManagedObjectContext MR_context];

// Create a new Person in the current thread context
ResearchType * research   = [ResearchType MR_createInContext:localContext];

// Set properties
research.researchCategory    = [info objectForKey:   @"Category"];
research.researchPrefix      = [info objectForKey:   @"Prefix"];
research.researchCategoryUrl = [info objectForKey:   @"Category Code Url"];
research.researchType        = [info objectForKey:   @"Type"];


research.researchCountry     = [info objectForKey:   @"Country"];
research.researchCountryCode = [info objectForKey:   @"Country Code"];
research.researchDate        = [info objectForKey:   @"Research Date"];
research.researchDevice      = [info objectForKey:   @"Device"];
research.researchLimit       = [info objectForKey:   @"Limit"];

// Save changes
 [localContext MR_saveInBackgroundCompletion:^{

   savedResearch(research);
 }];

 }

---

    + (void) persistAppsFromArray: (NSArray *) arrayOfApps inResearch: (NSDictionary *) info  {


// Get the local context
    NSManagedObjectContext *localContext    = [NSManagedObjectContext MR_context];

 [localContext MR_saveInBackgroundCompletion:^{


     // predicates
     NSPredicate * predicateCategory = [NSPredicate predicateWithFormat:@"researchCategory = %@" , [info objectForKey: @"Category"]];
     NSPredicate * predicateType = [NSPredicate predicateWithFormat:@"researchType = %@" , [info objectForKey: @"Type"]];
     NSPredicate * predicatePrefix = [NSPredicate predicateWithFormat:@"researchPrefix = %@" , [info objectForKey: @"Prefix"]];

     NSArray * predicates = [NSArray arrayWithObjects: predicateCategory, predicateType, predicatePrefix, nil];

     // Composite predicate
     NSPredicate * predicateComposito = [NSCompoundPredicate andPredicateWithSubpredicates:predicates];

     ResearchType * researchBgContext = [ResearchType MR_findFirstWithPredicate: predicateComposito];

     for (NSDictionary * info in arrayOfApps) {

         AppInDb * app             = [AppInDb MR_createEntity];

         app.appName                  = [info objectForKey: @"App Name"];
         app.appItunesLink            = [info objectForKey: @"iTunes Link"];
         app.appBundleID              = [info objectForKey: @"Bundle ID"];
         app.appID                    = [info objectForKey: @"ID"];
         app.appPriceLabel            = [info objectForKey: @"Price Label"];
         app.appReleaseDate           = [info objectForKey: @"Release Date String"];
         app.appIconImageLink         = [info objectForKey: @"Image Link 100"];
         app.appDeveloperPageLink     = [info objectForKey: @"Developer Page Link"];
         app.appDeveloper             = [info objectForKey: @"Developer"];
         app.appRights                = [info objectForKey: @"Rights"];
         app.appDescription           = [info objectForKey: @"App Description"];
         app.appCategory              = [info objectForKey: @"App Category"];
         app.appCategoryNumber        = [info objectForKey: @"Category Number For Url"];


         // adding app to the related research (one to many relationship)
         [researchBgContext addAppsObject:app];



           }
       }];

     }

Answer 1

Try with this method:

[MagicalRecord saveInBackgroundWithBlock:^(NSManagedObjectContext *localContext)block { }];

There are a number of other methods you can use, but this should give you a good start. MagicalRecord will create the context for you and everything happens on the background thread. It will also save to the parent context automatically.

I recommend reading this great article: Core Data and Threads, Without the Headache by Saul Mora who's the person behind MagicalRecord. It's a great read which informs you about the many advantages of MagicalRecord.

Good luck!