A topic-centric list of HQ open datasets.

A list of semi to fully remote-friendly companies in tech.

Color Framework for iOS (Obj-C & Swift)

 A curated list of awesome applications, softwares, tools and shiny things for macOS.

Highly customizable tabBar and tabBarController for iOS

OS X and iOS application and framework to play with the Apple Push Notification service (APNs).

An UINavigationController's category to enable fullscreen pop gesture in iOS7+ system style with an AOP useage.

Elastic pull to refresh compontent developed in Swift

Unleashing the real power of Core Data with the elegance and safety of Swift

Custom transition between viewcontrollers holding tableviews. Each cell is animated to simulate a 'wave effect'.

A list of amazing Newsletters

CoreData wrapper written on Swift

A tiny log console to display information while using your iOS app. Written in Swift 3.

Find unused Objective-C imports.

Find memory issues & leaks in your iOS app without instruments

DGActivityIndicatorView is a great way to make loading spinners in your application look nicer.

A versatile popup for iOS

Categories on NSRegularExpression that make regular expressions more concise in Objective-C.

Generates a Swift Playground for any Pod.

Swiftline is a set of tools to help you create command line applications

Flexible progress bar written in Swift.

Beautiful social “like” buttons with counters for jQuery.

Generates a Photoshop (PSD) file from your app view hierachy.

Thread-safe NSTimer alternative that doesn't retain the target and supports being used with GCD queues.

A Swift framework that helps you decouple & modularise your UI component into small pieces of LEGO style's bricks.

An iOS UIView for presenting a minimalistic notification that doesn't block the UI and is highly configurable

iOS drop-in class for interactive coach marks with cutouts to spotlight the app's existing UI.

A simple keyboard to use with numbers and, optionally, a decimal point.

A Custom&Magical ActionSheet.

A custom segue for providing a blurred overlay effect.

Swift types for working with Money.

When UITableView(iOS) is empty,then it can automaticely make an empty overlay view

Protocol to handle initial Loadings, Emty Views and Error Handling in a ViewController & views

Used to print the structure of your application as you use it

A High-performance, Elegant And Easy-to-integrate Charting Framework..

A flat button inspired by Google Material Design's Paper theme.

A new container controller to easily push views on side like Path or Facebook.

Objective-c library for tracking keyboard in iOS apps.

A Swift based Future/Promises Library for IOS and OS X.

UITextField category that adds a shake animation like the password field of the macOS login screen.

Simple countdown UILabel with morphing animation, and some useful function.

ObjectiveFlickr, a Flickr API framework for Objective-C.

An emoji keyboard view that can replace the default iOS keyboard.

Alternative Emoji keyboard for IOS

YouTube Video Link Parser for Swift

YouTube Video Link Parser for Swift

TAOverlay is a minimalistic and simple overlay meant to display useful information to the user.

A simple project.pbxproj verifier

A custom animation for the UIRefreshControl

Peas is an open source Heroku-style PaaS written in Ruby and using Docker

WAAppRouting is a library to help you dealing with routing on your app by controllers. As a key point, it handles a stack of controllers!

Interface similar to the UITableView with UI similar to Pintrest.

A drop-in MapKit/MKAnnotation pin clustering library for MKMapView on iOS.

An iOS container view controller for pullable scroll view interfaces.

A gulp plugin for processing files with ESLint

A Mailbox style grid menu with a blurred background.

Medium's upper and lower Menu in Scroll.

A Swift NSPredicate DSL for iOS & OS X inspired by SnapKit, lovingly written in Swift, and created by the awesome peeps at KrakenDev.io!

Is the simplest way to insert a UITextView inside an expandable UITableViewCell.

A replacement of UIAlertController

RangeSeekSlider provides a customizable range slider like a UISlider.

Swift animation library for iOS, tvOS and macOS

A simple library to make authenticating tvOS apps easy via their iOS counterparts using Bonjour.

Easy to use, fast, and higher performance than UILabel.

Video view controller with Periscope fast rewind control

A floating navigation drawer with an interesting animated presentation written in Swift.

A circle progress view.

Better indicator view for iOS.

A cells of UITableView can be rearranged by drag and drop.

This generic SOAP client allows you to access web services using a your iOS and Mac OS X app.

iOS 7 Style PIN Screen for iPhone and iPad

A Simple Cocoa Weather Library.

A very simplifty animation framework. Powerby Facebook.

An iOS framework for creating JSON-based models. Written in Swift.

iOS Checkboxes inspired by Google's Paper Material Design.

Surfboard is a delightful onboarding library for iOS.

A simple way to debug your view hierarchy.

MPGNotifications is an iOS control that allows you to display customizable in-app interactive notifications.

Circle ProgressBar control for iOS.

User defined literals for Objective-C.

A Simple Tuner

A short description of CRPageViewController.

UITableView/UIScrollView Category to get really easy, smart and instant screenshot images for iOS 5+ devices.

High-performance DSP for audio on iOS and OSX with Novocaine.

A simple iOS video player in Swift

Protocols for your every day iOS needs

A flat button inspired by Google Material Design's Paper theme.

A Swift CoreData extension to bring some love and take the hassle out of common CoreData tasks.

The iOS and OS X neural network framework

Video Thumbnail ScrollView

slider view for choosing categories. add any UIView type as category item view .

A command line interface for smithing Ruby gems.

Enhanced transitioning between UICollectionView layouts in iOS.

iOS UITabBar inspired by Google's Paper Material Design.

Dropin replacement of UISwitch that 'infects' the parent view with the onTintColor when the switch is turned on.

An Objective-C proxy class for creating paged arrays

JMActionSheetDescription replace UIActionSheet and UIActivityViewController.

Share loading button

This component allows you to select circular map region from the MKMapView

menu based on Medium iOS app

A PDF toolset for iOS with an emphasis on form filling.

Simple and ready to use subclass of UITextField which uses NSRegularExpression to validate text with pattern you set.

DRDNetworking is a networking sdk started by IMF.

Custom animated iOS controls: Animated discrete slider, animated labels

Durandal is a networking sdk started by IMF.

The easiest way to prepare, play, and remove sounds in your Swift app!

Swift Web Server Gateway Interface.

Full clone of iOS number keyboard with customizable function button

UALogger is a logging tool for iOS and Mac apps.

MAFormViewController is designed for quick and easy UITableView form creation handling formatting, navigation, validation, and submission.

Simply the fastest way to transmit data between iOS/tvOS and OSX

A custom UIScrollView with a vertical parallax effect

Easy to use and flexible AutoLayout alternative for iOS 8+. Supports AsyncDisplayKit.

An emoji-based rating view for iOS, implemented in Swift.

Lightweight ad mediation for iOS to properly manage multiple ad networks dynamically including iAd and Google ads.

An abstraction layer for FirebaseDatabase and FirebaseStorage.

Bring life to CALayers with SpriteKit-like animation builders.

Interactive zoom transition for presenting view controllers written in Swift

A category on UIView that allows you to progressively download images providing seamless enhancement.

An iOS library for fast, easy, and safe threaded disk I/O.

An iOS stock chart library in Objective-C, K-Line.

Breeze through NSDate, NSDateComponents, and NSTimeInterval!

A simple to use, standard interface for authenticating to oauth 2.0 protected endpoints via SFSafariViewController.

Grand Central Dispatch Utilities

Simple coach mark library written in Swift

Subclassed UITableView/UICollectionView cells that auto calculate size when AutoLayout constraints are applied correctly. iOS 7+.

A 3D filter control that gives users a fun way to browse between many segments.

Minify CSS with CSSO.

Action button is a Floating Action Button inspired from Google Inbox implemented in Swift

Tattle UI control library for IOS

When object(iOS) is nil,then it can automaticely execute a block

Type-Safe Flux implementation for Swift.

Find inspiration with Shia LaBeouf & Orta Therox when it feels like programming just isn't working for you at the moment. You can do it, so get on with it.

AGWindowView is a UIView which can be added directly to UIWindow. It handles rotation and frame changes of statusbar for you.

Use VIPhotoView to view a photo with basic interactive gesture.

Create material design cards quick and easy.

Simple class for handling Local Authentication using Touch ID. Used in eHarmony iOS App.

Simple implementation of a UITableView styled as chat bubbles. It provides different base styles and it's easily customizable.

uiscrollview with strechy and parallax top view

NSAttributedString generation from NSString using XML, that can be easily extended.

Convert NSDictionary/NSArray into objects with predefined class.

CMHTMLView is UIWebView wrapper to provide easy access to show rich text content (HTML) with native look and feel.

Painless custom transitioning. Easy extend, easy setup, just focus on animations.

A custom loading bar for iOS

It is controllable UIView like Jog Dial

A horizontal scroll dial like Instagram

Lightweight class library for creating drop down list controls for iOS.

A horizontal scroll dial like Instagram

UICollectionView-based image carousel written in Swift

NMPopUpViewSwift is a simple class for iOS that shows nice popup windows

Easily cache objects in memory, to files, a database or not at all.

Content Mode Animatable Image View, change image view's content mode with your animation!

Action sheet allows including your custom views and buttons.

`AXPopoverView` is an iOS customizable view that displays a bubble style view.

iAppInfos allows an access to important App informations : version, model, Mobile provisionning infos

Flexible and highly configurable auto complete view, attachable to any UITextField.

Snoozing for everyone

Drop-in iOS Audio Player built on top of BASS-library

An accordion controller for iOS

A category for UIColor that adds flat UI color methods inspired by Google's Material Design, Paper.

A class that allows you to assign multiple delegates.

An iOS custom date picker in the flat design.

Library provides easy to implement variation of Android (Material Design) Floating Action Button for iOS. You can use it as your app small side menu.

UIView subclass that reproduces the waveform effect seen in Siri on iOS 7 / iOS 8

An Objective-C implementation of Google proto buffer for iOS

SwiftyText in Swift based on Text Kit

Simple UITabBar/UITabBarController replacement made by using AutoLayout

base64 is a command line utility which encodes and decodes files in this format. It can be used within a pipeline as an encoding or decoding filter, and is most commonly used in this manner as part of an automated mail processing system.

Bluetooth library written in Swift. Mapping services and characteristics to models.

Introduces a prettier About Window.

A triangle shaped corner label view for iOS written in Swift.

Easy, clean and fast UIPageController with Control Buttons.

A calendar view

Simple and customisable stepped progress bar for iOS written in Swift

A UINavigationController subclass that support interactive UINavigationbar with hidden or show.

Automatic network activity logger for iOS and OSX, written in Swift.

Custom UIPageControl

Powerful file downloads manager in Swift

Progress HUD inspired by Tumblr app

The UINavigationController missing methods, push/pop with completionBlocks.

The UINavigationController missing methods, push/pop with completionBlocks.

轻量级图像选择框架

Declarative view styling in Swift.

轻量级的上拉／下拉刷新控件

GPS data from GPX files

An drop-in replacement for UIPercentDrivenInteractiveTransition

SVG Rendering Library for iOS

Automatically index your CoreData objects to CoreSpotlight on iOS 9

Category on NSError that stores the stack trace of the creation of the NSError object for later retrieval.

Custom view animation

PeekView supports peek, pop and preview actions for iOS devices without 3D Touch capibility

A drop-in replacement for UILabel, which automatically adds a scrolling marquee effect when needed.

iOS Utilities

Simply organize your controllers in a stack of sheets inspired by Evernote Food 2.0 app.

Simple animation of splash screen like in Twitter App for iOS 7, 8 & 9

Another block based UIActionSheet but more elegant. Elegant to code and elegant to see.

Component which presents a dismissible view from the bottom of the screen.

iOS Custom UIScrollView Control for paging UIViews

Kurento Toolbox for iOS

Simple selection dialog

Simple selection dialog

A simple way to make UIScrollView support pull-to-refresh & infinity-scroll

Swift Library using Core Animation to make custom switch

A simple category to add copy functionality to UILabel.

Swifty Interaction with VIPER

RHManagedObject is a library for iOS to simplify your life with Core Data.

YMSwipeTableViewCell is a lightweight library that enables table view cell swiping.

An Objective-C wrapper around the open-source FreeTDS library

`TypedDefaults` is a utility library to type-safely use NSUserDefaults

Like UIDatePicker, but without the days

Completion and Diagnostic for C/C++/Objective-C using Clang Command

Highly customizable mentions library

Abstract text processing and pattern matching engine in Swift. Converts text into NSAttributedStrings. Builtin markdown support.

基于AFNetworking的网络库封装

Hack the Simulator in your tests (grant access to photos, contacts, ...)

Swift Collection Data Structures Library

Detects when your Xcode tests are being run in a CI server, and makes them pass.

Futures without nesting issues.

Simple scrollable horizontal control, alternative to UISegmentedControl

Amazing animated switch activity indicator written in swift

NSURLSession and NSOperationQueue working together.

Simple yet powerful image downloading, caching and GIF playback framework.

a easy side view controller.

HexColor is a simple extension that lets you initialize UIColors the way they were meant to be initialized: With hex integer values.

An easy-to-use utility that will automatically resize views whenever a keyboard appears

A page control to hint users that elements are in fact part of a grid

Macro collection for daily usage

Fancy iOS7 style menu.

Simple, fast, colorful, flexible and customizable NSLog replacement.

A mesmerizing view with lots of options. It is meant to be used with BFRadialWaveHUD, but you are free to take it :)

Icon font library for Swift. Currently supports Google Material Design Icon

Terminal Colors for Swift

A simple iSort like header sorting and duplicate removal plugin for Xcode

Geometry is a UIView and CGRect extension that lets you work with view and rect geometry easier.

Helpers for using value types with YapDatabase.

Effortless emoji-querying in Swift

Swift HSV Color Picker

A quick and simple way to authenticate an Instagram user in your iPhone or iPad app.

An iOS custom alert view.

Subclass of UIImageView to create a circle avatar image view with configuration border width and border color

A progress HUD using BFRadialWaveView.

Simple Socket Networking

An Objective-C wrapper for the Google Places Autocomplete API

P2P Framework for realtime collaboration in Swift with independent modules for WLAN, Bluetooth and Remote support

OAuth that just works!

Presents your view controller with a blurred image of the background behind it.

GCTagList like iOS Mail app's sender or recivers tags.

FSK Library for iOS interface with Arduino Development.

A fast & minimal embedded full-text search library for Objective-C.

A light weight & simple & easy camera for iOS by Swift.

AutoLayoutKit in pure Swift.

View that displays GeoJSON map with selectable countries.

Storage classes for datasource based controls.

IncrementableLabel is the easiest way to have incrementable numbers in an UILabel!

Swift implementation of the Float Label Design Pattern by Matt D. Smith as a sub call from UITextField

Interactive Keyboard Controller for Swift

Animated Play and Pause Button written in Swift2.0, using CALayer, CAKeyframeAnimation.

A Swift library to provide a animated action sheet and alert

An iOS custom font loader

Digital Ruby Color Picker

SpatialDBKit is the spatial RDBMS for iOS.

Customizable and interactive animated notification UI control.

Linkedin Oauth Helper, depend on Linkedin Native App installed or not, using Linkdin IOS SDK or UIWebView to login

EasyTransition is a simple library for make a transition in iOS.

Simple and easy logging in Swift.

RAlertView 0.1.1

Alternative to UIActivityViewController

A testable, Rx* wrapper around MultipeerConnectivity

Another container controller.

A customizable and elegant alternative to UIActionSheet with support for block syntax.

Objective-C OpenPGP framework built on foundation of NetPGP library

A UIDevice category to determine if the passcode is currently set on the device or not.

Generic table view & collection view datasources in Swift, for use with YapDatabase.

INSStackViewForms - iOS library to create dynamic UIStackView forms

Draggable blurred view. This control is inspired by the brilliant work of César Pinto Castillo's AMBlurView

A progress view based on Medium web app.

GCD based HTTP server for Swift 2 (Linux ready)

Deprecated. Use UIViewController+BlockSegue instead of that.

UIViewController category which allows to use a block to prepare segue instead of ugly -prepareForSegue method.

Useful tools you need to launch your app.

Drop-in replacement for the limited UIAlertView input options.

Safe, statically-typed, store-agnostic key-value storage!

An easy way to control manually the language in your application.

Weakly associate an object with a reference to one of its methods

EMCCountryPickerController is a view controller allowing users to choose and filter countries in a list.

Unit test presented view controllers, alerts, and action sheets for iOS

A flat view inspired by Google Material Design's Paper theme.

Use the wonderful ACE editor in your Swift Cocoa applications

Bridge for Javascript and Objective-C in hybrid app development, using JavascriptCore

ObjC library that supports objc-obfuscator gem

Swift protocols for encoding/decoding value types.

Display UIDatePicker inline easily!

A simple Swift Keychain Wrapper for iOS

Customizable simple popup view in iOS.

A Dropbox v2 client library written in Objective-C

iOS Validation Library

Easily switch between different real-time Objective-C frameworks without any code changes.

OHPDFImage allows you to use a PDF as a vector UIImage

This is a class designed to show an image or video, and blur & shrink the background. Similar to the Facebook app.

STDeferred is simple implementation of Deferred object.

A universal and extensible account system for iOS

Automatic token detection support to use together with the Knuff Mac app.

Easy library to fetch and edit data from and to plists on the fly (XCode).

Particle iOS Cloud SDK for interacting with Particle powered devices (Core/Photon/Electron)

A flexible Matrix library for Objective-C, which interfaces BLAS, LAPACK and vDSP functions via the Accelerate Framework

JS to Objective-C... and back again.

A multi-platform, decentralized, auto-discover and auto-connect mesh networking and messaging API

A circular or linear shaped view where you animate the angle changes.

Node.js inspired EventEmitter for Objective C.

Helper to call a phone number from an iPhone using the telpromp scheme.

A ViewController that manages 3 contained viewcontrollers

Add syntax highlighting to JSON objects in Objective C for both Cocoa and iOS without using HTML.

Easy, Android-compatible hex strings to UIColor.

RFC 4648 Base32 implementation in Objective-C ARC.

Unofficial wrapper to quickly launch Google Maps for iPhone from your app.

A declarative Swift DSL for your view tracking needs

A simple utility class to monitor real time changes in a directory, such as the documents dir for an app with File Sharing enabled.

A tiny class to replace UIAlertView.

KosherCocoa is a Hebrew Calendar, Jewish Prayer, and Jewish Holiday Library for iOS, tvOS, and watchOS.

Functional chaining and promises in Swift

A Swift UITabBarController with a larger center tab.

A flow layout style UICollectionViewLayout that fills the full width of the collection view

Mock alerts and action sheets for iOS unit tests

FactoryGirl and fixture loader for iOS.

A UITableView and UICollectionView delegate and datasource that provides a simpler unified interface for describing your sections and cells.

A libary that helps you build table views without re-inventing the data source

Simple Objective-C solution for text validation.

A quick and simple way to authenticate a Dropbox user in your iPhone or iPad app.

A UIView subclass with four configurable borders via storyboard

Done animation on HUD made with Swift

A simple control designed for guiding a user through a controlled flow

UIViewController with FBDialog inside to send Facebook app request.

Icon font library for Swift. Currently supports Entypo

Invitation functionality for use in conjunction with the Branch iOS SDK

Instantly draw beautiful tables to your terminal.

GTToast is a library written in Swift which allows toast notifcations to be displayed. You can create toasts with text and/or images.

A Swift framework for working with Imgix.

Simple, Customizable notification panel (iPhone & iPad)

A framework for easily creating a hybrid app from a mobile friendly web app.

In App Purchase Manager framework for iOS

iOS SDK for the open source back end BaasBox. See http://www.baasbox.com

Android style overflow button for iOS

UIView subclass to manage a collapsing and expanding header view.

In-App Browser for iOS Apps Support UIActivity.

send your user to various locations within iOS' Settings app

An UIActivity subclass for Sharing on Google+

Wave animation pull to refresh for iOS

CommandBus is a light weight Command Bus implementation written in Swift

Swift types for working with Foreign Exchange.

WATokenFieldView is custom view that let you add token view in a view while typing/searching.

Lokalise framework for OTA localization for iOS.

A UIView category to provide rich toast notifications.

Share information between your applications and extensions

Swift Open Weather Map API is a wrapper around http://openweathermap.org.

One line lazy property definition, with auto triggering, custom selectors

ARSlidingPanel is a realization of sliding-up panel for iOS

CheckmarkSegmentedControl is a customisable alternative to UISegmentedControl.

Collection of custom iOS segues.

An extremely simple JSON helper written in Swift.

A filter bar, similar to a UISegmentedControl.

A library for easily creating static table views programatically.

A simple Progress View that allows colour changing via Interface Builder

Custom Switch for iOS.

Atomic is a fast, safe way to make values atomic (thread-safe).

A simple, elegant pop-up menu view.

Breeze is a lightweight CoreData manager written in Swift!

UIColor Category for Brand Colors.

Unofficial wrapper to quickly send messages with WhatsApp for iPhone.

MRLocalNotificationFacade is a class that wraps most of the APIs required for dealing with local notifications in iOS.

AlamofireXMLRPC brings XMLRPC functionalities to Alamofire.

Ionicons for Swift and iOS

A JSON framework that can deserialize the JSON string into real objects, with 0.1 configuration.

Fully customizable sidebar controller

UIView category providing bouncing functionality

UIButton, but bouncier and with your own icons.

JSON declarative validating and binding library written in Swift

Most powerful Swift object-mapping library

A very simple category that sends out an NSNotification whenever the device is shaken.

Cropping a rect or a circle from images!

Flexible HTTP client for Objective-C and Swift

A Swift router implementation

an image auto scroll player.

Your application's favorite web request library.

Open Source Request handeling/managing on iOS snf OS X

A replacement for UIImagePickerController that can select multiple photos.

Tapglue enables mobile developers to create products with a social graph and a news feed in hours instead of weeks.

Simple and easy-to-use record button for iOS, that enforces a long press, similar to Instagram

Single selection menu with cool animations

A simple 'Table View Pager' for iOS which is inspired by Android's view pager.

An easy way to customize styles to any UIResponder from the Interface Builder

We can add some stored objects to Swift extension

A flat button for use in a collection view cell inspired by Google Material Design's Paper theme.

WeChatSDK for Cocoapods convenience.

A library for using the ArcGIS Geotrigger Service with iOS.

Extends the native Swift string with a method to easily decode HTML entities.

SwiftyRegExp is a simple and convenient Swift wrapper around NSRegularExpression. It was inspired by Ben Scheirman's "RegEx in Swift" post

Particle iOS Cloud SDK for interacting with Particle powered devices

Simple and basic string obfuscating - based on UAObfuscatedString by Matt Coneybeare

DocuSign REST API

A testable, Rx* wrapper around MultipeerConnectivity

Convert XML to an NSAttributedString.

An Easy Way to Intergate Scrolling Header

Bundles a couple of useful build scripts, and a way of keeping environment dependent properties

Numeric Operations for Swift

a cycle scrollview with reuseable pool.

An NSProxy for converting strong references into weak ones.

Simple Swift JSON representation supporting subscripting and pattern matching.

iOS SDK for CyberSource

A suite of extensions to ease using FileManager for common tasks.

BiometricAuthenticationFacade is a high level wrapper for LocalAuthentication framework.

CoreDataServices contains a set of helper classes/extensions to abstract out a lot of the boilerplate that you get with Core Data.

ADiOSUtilities is collection of static libraries with re-useable iOS awesomeness.

The Vimeo iOS Upload SDK

iOS photo chooser optimized for swiftness

An AVPlayerItem subclass which helps with handling video playback key-value observation.

Swift helper for REST models

Made sideways or upside down images upgright again.

Integrates Google Fusion Tables into iOS apps.

An unofficial MTA SDK Cocoapods repository.

A pull to refresh control that has a simple, elegant spinner

Elegant helpers to improve the swift syntax

实时获取设备网络

An Assistant for AutoLayout in Swift.

iOS version of Checkout Kit that implements Card Tokenisation

This is the Applanga SDK

Integrate your iOS app with stomt.com

:art: Add some color to your swift command line tools.

Simple Apple Swift result type

A framework that makes it easy to incorporate your Desk site’s support portal into your iOS app.

Sailthru Mobile iOS SDK for integrating with https://mobile.sailthru.com messaging and analytics service.

Swift framework building on SwiftyJSON to provide convenient and type safe decoding of objects/values from JSON.

The Official iOS SDK of Tencent Open API.

A FetchedResultsController implementation that abstracts out the boilerplate for both UITableView.

iOS library for mPulse Analytics

Drop-in style Image File Name tracking debug tool

Translation Markup Language for Objective C.

My collection of Objective-C helpers

The 7digital iOS SDK helps you use the 7digital API.

Citrix ITM Radar Runner for Apple iOS and MacOS.

Getui SDK

CollabNet, Facilitating Collaborative Software Development

Key-Value Observing for pure Swift objects.

Functional Test Automation library for iOS applications.

A web browser module for your apps.

A Swift micro library for generating Sunrise and Sunset times.

A web browser module for your apps.

Unleashing the real power of Core Data with the elegance and safety of Swift