A powerful and simple Core Data wrapper framework written in Swift.

Using the framework

The basics

Persistent container

AlecrimCoreData provides a default PersistentContainer class that can be used as is, extended, or not used at all. If used, it will help you with several Core Data related tasks.

(The provided PersistentContainer class can be used with previous versions of Apple operating systems too [iOS 9, for example].)

It is possible to use the framework with a "vanilla" NSPersistentContainer if you prefer. In this case you will have the liberty to configure the Core Data stack as you want, but only for newer Apple operating systems (iOS 10, for example).

// Initializes a `PersistentContainer` instance with default options.
let container = PersistentContainer(name: "ModelName")

Generic persistent container

If you have subclassed the default manage object context class or want to change some of the persistent container behaviors you can use the GenericPersistentContainer class for this:

class MyContext: NSManagedObjectContext {
    // ...
}

class MyPersistentContainer: GenericPersistentContainer<MyContext> {
    // ...
}

(The PersistentContainer class is a GenericPersistentContainer<NSManagedObjectContext> subclass actually.)

Table

The generic Table<T> struct is the base for AlecrimCoreData functionality and is where the fun begins. T, in this case, is a NSManagedObject subclass type.

// Extends the `NSManagedObjectContext ` class to include entity table properties.
extension NSManagedObjectContext {
    var people:      Table<Person>     { return Table<Person>(context: self) }
    var departments: Table<Department> { return Table<Department>(context: self) }
}

Fetching

Say you have an NSManagedObject subclass type called Person, related to a Department. To get all of the Person entities as an array, use the following methods:

for person in context.people {
    print(person.firstName)
}

You can also skip some results:

let people = context.people.skip(3)

Or take some results only:

let people = context.people.skip(3).take(7)

Or, to return the results sorted by a property:

let sortedPeople = context.people.orderBy { $0.lastName }

Or, to return the results sorted by multiple properties:

let sortedPeople = context.people
    .orderBy { $0.lastName }
    .thenBy { $0.firstName }

Or, to return the results sorted by multiple properties, ascending or descending:

let sortedPeople = context.people
    .orderByDescending { $0.lastName }
    .thenByAscending { $0.firstName }

If you have a unique way of retrieving a single entity from your data store (such as via an identifier), you can use the first method:

if let person = context.people.first({ $0.identifier == 123 }) {
    print(person.name)
}

Filtering

You can filter the results using the filter method:

let filteredPeople = context.people.filter { $0.lastName == "Smith" }

You can combine multiple filters and other methods as well:

let filteredPeople = context.people
    .filter { $0.lastName == "Smith" }
    .filter { $0.firstName.beginsWith("J") }
    .orderBy { $0.lastName }
    .thenBy { $0.firstName }

Or:

let filteredPeople = context.people
    .filter { $0.lastName == "Smith" && $0.firstName.beginsWith("J") }
    .orderBy { $0.lastName }
    .thenBy { $0.firstName }

Counting

You can count entities in your persistent store using the count method.

let peopleCount = context.people.count()

Or:

let filteredPeopleCount = context.people.count { $0.lastName == "Smith" }

Or:

let filteredPeopleCount = context.people
    .filter { $0.lastName == "Smith" }
    .count()

Create, update, delete and save

Creating and updating entities

When you need to create a new instance of an Entity, use:

let person = context.people.create()

You can also create or get the first existing entity matching the criteria. If the entity does not exist, a new one is created and the specified attribute is assigned from the searched value automatically.

let person = context.people.firstOrCreated { $ 0.identifier == 123 }

Deleting entities

To delete a single entity:

if let person = context.people.first({ $0.identifier == 123 }) {
    context.people.delete(person)
}

To delete many entities:

context.departments.filter({ $0.people.count == 0 }).deleteAll()

Saving

You can save the data context in the end, after all changes were made.

container.performBackgroundTask { context in
    let person = context.people.firstOrCreated { $0.identifier == 9 }
    person.firstName = "Christopher"
    person.lastName = "Eccleston"
    person.additionalInfo = "The best Doctor ever!"

    do {
        try context.save()
    }
    catch {
        // do a nice error handling here
    }
}

Strongly-typed query attributes and ACDGen

Another important part of AlecrimCoreData is the use of strongly-typed query attributes. A lot of boilerplate code is required to support strongly typed queries. With this in mind, the ACDGen tool was created. All you have to do is to point ACDGen to your managed object model and the source code for the entities is automatically generated, including the AlecrimCoreData query attributes if you want.

Using the generated strongly-typed query attributes is completely optional, but with them the experience with AlecrimCoreData is greatly improved. The use of strongly-typed query attributes requires a project that has generated extensions of it's model classes using ACDGen.

ACDGen source code is avaible from the "ACDGen/Source" folder. There is a command line tool called acdgenp that can be built from the same project.

If you use ACDGen, consider setting Manual/None in your model as the selected option in Xcode for automatically entity code generation.

Advanced use

OK. You can write code like this:

// No data access is made here.
let peopleInDepartments = container.viewContext.people
    .filter { $0.department << [dept1, dept2] }
    .orderBy { $0.firstName }
    .thenBy { $0.lastName }
        
let itemsPerPage = 10  

for pageNumber in 0..<5 {
    print("Page: \(pageNumber)")

    // No data access is made here either.
    let peopleInCurrentPage = peopleInDepartments
        .skip(pageNumber * itemsPerPage)
        .take(itemsPerPage)

    // Now is when the data is read from persistent store.
    for person in peopleInCurrentPage {
        print("\(person.firstName) \(person.lastName) - \(person.department.name)")
    }
}

But you can do even more with AlecrimCoreData. You are invited to read the code and discover more possibilities (and to help us to improve them and create new ones).

Advanced methods

There are methods for aggregating, asynchronous fetching in background and many others. You can read the AlecrimCoreData documentation at http://cocoadocs.org/docsets/AlecrimCoreData for more information.

Ordering and filtering

You can order and filter entities not using the AlecrimCoreData query attributes at all. In this case you lose the strongly-typed attributes, but gain in flexibility. You can even mix the two approaches without any problem.

Ordering

You can order the entities using NSSortDescriptor instances:

let sortDescriptor: NSSortDescriptor = ...
let orderedPeople = context.people.sort(using: sortDescriptor)

Or:

let sd1: NSSortDescriptor = ...
let sd2: NSSortDescriptor = ...

let orderedPeople = context.people.sort(using: [sd1, sd2])

You can also use the sortUsingAttributeName:: method:

let orderedPeople = context.people.sort(usingAttributeName: "lastName", ascending: true)

Filtering

You can filter entities using NSPredicate instances:

let predicate: NSPredicate = ...
let filteredPeople = context.people.filter(using: predicate)

Using

Minimum Requirements

• Swift 3.0
• Xcode 8.0
• macOS 10.12+ / iOS 9.0+ / tvOS 9.0+ / watchOS 2.0+

Installation

CocoaPods

CocoaPods is a dependency manager for Cocoa projects. You can install it with the following command:

$ gem install cocoapods

CocoaPods 1.1.0+ is required to build AlecrimCoreData 5.2+.

To integrate AlecrimCoreData into your Xcode project using CocoaPods, specify it in your Podfile:

source 'https://github.com/CocoaPods/Specs.git'
platform :ios, '10.0'
use_frameworks!

target '<Your Target Name>' do
    # pod 'AlecrimCoreData', :git => 'https://github.com/Alecrim/AlecrimCoreData.git', :branch => 'develop'
    pod 'AlecrimCoreData', '~> 5.2'
end

Then, run the following command:

$ pod install

Manually

You can add AlecrimCoreData as a git submodule, drag the AlecrimCoreData.xcodeproj file into your Xcode project and add the framework product as an embedded binary in your application target.

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Contact

• Vanderlei Martinelli

License

AlecrimCoreData is released under an MIT license. See LICENSE for more information.