I worked on projects in which releases had to be delayed because of some libraries that were not going to be updated for new versions of iOS. And dependencies always come with costs: If something does not work, you now have a massive chunk of code you need to understand and debug. NetworkManager that tells the caller, which is usually a view controller, what type of data the API returns. The code snippets below are here to help jog your memory when it’s been a while since you’ve worked in Core Data. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence. @crnk/angular-ngrxAngular help… AlamoFire has an extension to request images asynchronously through the First of all, this is an opinionated subject, and you will find many opinions on this topic. Working with Core Data used to be verbose and it is the framework's verbose API that led to the emergence of many, many third party libraries over the years. Mind you; the problem is not in the number of properties or methods. Even if you use the iOS SDK correctly if you structure your code in the wrong way you end with all sorts of problems in your app. While it has a point, that approach doubles the types in your project and introduces a lot of boilerplate code. This cheat sheet is a handy reference to keep you productive with Core Data and Swift! You may be able to as well. And since we don’t need any particular configuration, the Third-party libraries also have large documentation, FAQs, migration guides, and many questions on Stack Overflow. Step 1: In the ConfigureServices(IServiceCollection services) method of Startup.cs near the bottom just above “.AddMvc()” I added the line below: Step 2: Below that in Startup.cs in the Configure(IApplicationBuilder app, IHostingEnvironment env) method I added the line below just before .UseMvc(): Step 3: Finally in the actual Controller file I added a directive just above the API calling code that said to use ResponseCaching like below: If ResponseCache is good for you to use, you need to understand how you would use it. And this rule, of course, includes me too. This is again some information that the caller needs to understand because the type exposes an interface that must be used in specific-yet-unspecified ways. In the rest of this article, we will create a simple app to fetch the top question about iOS development on Stack Overflow. We will just transform any error into a Core Data is great at managing object graphs. url computed property assembles the full URL for the resource using the base URL for the API, the Notice that the latter are hardcoded for our example, but you can easily transform them into requirements for the It might be true for straightforward network requests, but I would also dispute that. Writing the networking layer of an iOS app, though, is not a simple task. For the whole page to render, the browser needs to retrieve each resource separately and does so in a single session. Since network requests to REST APIs go through the internet, they rely on protocols and standards you need to understand if your app relies on the network to retrieve its data. We’ll need an object that can retrieve the data and construct our domain object from the encoded data. When it comes to parameters, you might have noticed we have two options: either the query string in the URL or the HTTP headers. ASP.NET Core supports two levels of response caching. There are a few things you have to do in order to enable caching. And it did not hurt the data security, the truth of the information, or the user running the application. We now have to transform the JSON data we get from the API into our model types. We place this code again into a protocol extension: Don’t forget to add a weak self reference to the capture list of the completion handler of any asynchronous method like a method to transform the data it receives into a model type; a method to start the asynchronous data transfer; a callback to pass the processed data back to the caller. Saving to Core Data. An easy way to understand the idea is thinking about how your browser loads a web page. APIResource. All remote resources, regardless of their type, share a standard interface. All we need to do then is to call its I have been, for a long time, an advocate of putting code that transforms data into model types, since it’s part of an app’s business logic. Do I need to survive restarts of my application and keep caching? This is something I don’t get. I ran this 10 times to be sure the calls were all about the same. nil value, which is enough in many apps you write anyway. The regular “/” endpoint and then a “/majorcontrols” endpoint. Our app is finally complete. // Parse the data in the response and use it, "https://www.gravatar.com/avatar/f847f4085ff4144dfeffef53ed020b1d?s=128&d=identicon&r=PG", "Vertically align text to top within a UILabel", "https://api.stackexchange.com/2.2/questions?order=desc&sort=votes&site=stackoverflow", Representational State Transfer architecture or REST, this request file in the AlamoFire library, As you scroll through a table view and cells get reused, You can find the complete Xcode project on GitHub, the four-layered version described in Apple’s documentation, keeping model types decoupled from data decoding, Model-View-Controller in iOS: A Blueprint for Better Apps, Become an iOS Developer in 2020: The Ultimate Guide, Passing Data Between View Controllers in iOS: the Definitive Guide, Network Requests and REST APIs in iOS with Swift (Protocol-Oriented Approach), JSON Decoding in Swift with Codable: A Practical Guide. It did help me. A common one is to put the shared code in a generic method that can be reused and then break a lengthy conditional statement into separate ones. That is what I am running this on. In this article, we will look at each aspect, one by one. While Core Data should typically not be treated as a store that has a concept of primary keys, we can apply a unique constraint on one or more properties of a Core Data model. You also need to update the UI of your app and show to the user that data is being fetched over the network. What I cover in this series on Core Data is applicable to iOS 7+ and OS X 10.10+, but the focus will be on iOS. Notice one final thing: we need to store each API request in the Now that we have model types to represent the data we receive, we can finally fetch some data from the Stack Exchange API. You usually don’t instantiate a data task yourself. Again feel free to go to the GitHub repo to see the actual code setup. In this series, I will work with Xcode 7.1 and Swift 2.1. Now that we have the response in the web browser, let’s do some coding in Xcode. A URL has different components, but in the context of REST APIs, we are usually interested in just three: URLs though, are just a part of what you need to understand to communicate with a REST API. Swift can bring clarity to our code, thereby making it easier in some ways to use Core Data. But keep that approach in the back of your mind, since it might be useful someday. Interface pollution is a symptom of the violation of another SOLID principle, the Interface segregation principle. Moreover, with such a method, it’s not the To make asynchronous network calls, you need to use many features of Swift and UIKit, like the URLSession class and the Codable. You can move into a separate parser class, as I often see, but you will just move the problem somewhere else. Open ViewController.swift, add the following Core Data module import below the UIKit import: import CoreData This import is all you need to start using the Core Data API in your code. Overview. Diffable Data Sources were introduced at WWDC 2019 as a replacement for UICollectionViewDataSource and UITableViewDataSource.The API is available on iOS 13 and up and makes it easy to set up lists of data in which changes are managed through so-called snapshots. Decodable protocol. You can find the complete Xcode project on GitHub. Network requests in iOS apps don’t happen in a vacuum. URLSession is straightforward. As we have seen, not all our network request are sent to a REST API. Working with JSON in Swift If your app communicates with a web application, information returned from the server is often formatted as JSON.You can use the Foundation framework’s JSONSerialization class to convert JSON into Swift data types like Dictionary, Array, String, Number, and Bool.However, because you can’t be sure of the structure or values of JSON your app … If we don’t, ARC will deallocate immediately after we create it and we won’t get a callback. Wrapper  structure because, for consistency reasons, the data of every response is wrapped in another JSON object. And since I was so shocked at how easy this was for .NET Core Web APIs I was thinking others may want to learn this quickly as well. As much as I like to keep responsibilities separate in my code, there is no need to over-engineer it for its own sake. Beware though that binary data does not come along with the initial response, to keep the latter lightweight. 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