Guides to building an iOS app
Plain answers to the questions people ask before and after they build an iPhone app, written the way we would answer them on a call, with Apple’s sources linked.
Cost and planning
- 8 min readHow much does it cost to build an iOS app?The honest answer is a range. The useful part is knowing what moves a project around inside it, so this guide explains the price of a native iPhone app the way we scope one.
- 6 min readHow long does it take to build an iOS app?Most native iPhone apps we build take 8 to 16 weeks from kickoff to the App Store. This is where that time goes, what stretches it, and what you can do to launch sooner.
- 8 min readHow much does it cost to build an AI app?An AI app has two price tags: what it costs to build, and what it costs every time someone uses it. The second one decides whether the business works, so this guide covers both. Four of the five apps we run ourselves are AI apps, so this is the arithmetic we do for our own products too.
- 6 min readWhat does it cost to maintain an iOS app?Launch is the start of an app’s costs, not the end. Apple ships a new iOS every year, raises the minimum SDK every spring and releases new devices. This guide lists what you will pay for after launch, and how to plan for it.
- 7 min readFreelancer, agency or in-house: who should build your iOS app?There is no single right answer, and we are an agency, so read this with that in mind. Each option is the right one for some products at some stage. This is how to tell which one is yours.
- 6 min readHow to write an app brief, with a free templateA good brief does not need to be long. It needs to answer the questions that decide the scope, the price and the timeline. This is the template we would ask you to fill in, and how to answer each part.
Native or cross-platform
- 7 min readSwift vs Flutter: which should you choose for an iPhone app?Flutter is a good framework, and for some products it is the right one. We build only in Swift, so here is the comparison as fairly as we can make it, including when we would tell you to use Flutter instead.
- 6 min readKotlin Multiplatform vs native Swift for iOSKotlin Multiplatform is the cross-platform option that can keep the most of iOS native, because it shares logic while leaving the interface in SwiftUI if you want. Here is how it works, where it helps, and where native Swift is still simpler.
Engineering
- 7 min readSwiftUI vs UIKit: which should you use for a new iOS app?Most new iPhone apps should start in SwiftUI. Most good iPhone apps still use a little UIKit. This is how to decide where the line sits for yours.
- 12 min readStoreKit 2 subscriptions in Swift: a practical guideStoreKit 2 made in-app purchases in Swift far simpler than the original API, which Apple deprecated in iOS 18. This guide walks through a subscription from App Store Connect to a working paywall, with the code we would write.
- 9 min readSyncing app data with CloudKit: SwiftData, Core Data or CKSyncEngineIf your app’s data belongs to the person using it, CloudKit can sync it across their devices without a server of your own. There are three main ways to use it. This guide explains which to pick, and the rules that catch teams later.
- 9 min readOn-device AI on iPhone: Foundation Models, Core AI and Core MLSince iOS 26, any app can use the language model behind Apple Intelligence, and iOS 27 adds Core AI for running your own models on the device. This is a map of the options, what each one is good for, and where the limits are.
- 8 min readiPhone Duo: how to get your app readyiPhone Duo goes on sale on 23 October 2026. It has two displays and a hinge, and every app will run on it. Whether yours looks right depends mostly on how it was built. This is what changes and what to check.
- 8 min readWhat’s new in iOS 27 for app teamsiOS 27 arrived in autumn 2026 with Xcode 27. These are the changes that affect what you build, what you submit and how you sell, without the keynote language.
App Store
- 10 min readWhy apps get rejected by App Store review, and how to fix itMost rejections are not about the idea. They are about a crash, a missing demo account or a screenshot that shows the wrong thing. This guide goes through the common ones, guideline by guideline, and what to do about each.
- 8 min readApp Review Guidelines changes: what Apple updated, and what to doApple rewrites parts of the App Review Guidelines several times a year, usually with a short changelog and little explanation. This page keeps track of the recent updates and says, for each one, which apps it affects and what to do.
- 10 min readHow to publish an app on the App Store, step by stepPublishing an iPhone app is a sequence of small, well-documented steps, with a few that catch people out. This is the whole sequence in order, with Apple’s current requirements.
- 7 min readApp Store creative assets: product page headers and search result imagesSince autumn 2026, the App Store lets you put a brand image or video at the top of your product page and on your search result, not only screenshots. This guide covers what the new assets are, their specifications, what App Review accepts and how to design them.
Growth
- 9 min readApp Store Optimization checklist: every field, in orderMost ASO advice is guesswork about a ranking system nobody outside Apple can see. This checklist sticks to what Apple says counts, and to the fields you control.
- 7 min readApp Store keyword research: how to choose your wordsYou get 30 characters of name, 30 of subtitle and 100 bytes of keywords in each language. Keyword research is deciding what goes into that space, and it is mostly careful writing.
- 7 min readHow to localize your App Store listingThe App Store supports metadata in 50 languages. You do not need all of them. This guide covers which ones to start with, what to localise in each, and how to keep screenshots in step with the text.
- 8 min readiOS paywall best practices: what Apple requires, and what worksA paywall has two jobs: to convince people, and to pass App Review. Apple is specific about the second, and its rules happen to make the first easier. This guide covers both.
- 6 min readiOS app onboarding best practicesThe best onboarding is the one people barely notice. Apple’s guidance is to make it fast, fun and optional, and to teach by doing. Here is how that turns into screens.
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