Custom iPhone apps
Native apps written in Swift with SwiftUI for most screens and UIKit where fine control is still needed. Built around your workflows rather than a template.
Native apps for Apple devices Austin, TX · since 2018
iOS App Development Company Building Native Apps for iPhone and iPad
We build iPhone and iPad apps in Swift that follow Apple's design rules, use the platform's own features well, and get through App Review without drama.
678apps built
465+clients
Top 4%developer intake
10M+downloads by client users
From $4,500free scoping call
Overview
Native iPhone App Development, Done the Apple Way
An iOS app development company should know Apple's platform well enough to tell you what it rewards and what it rejects. SIZ Group has designed and developed 678 apps since 2018, and a large share of that work has shipped to the App Store. We know where Apple's guidelines get strict, which frameworks are worth adopting, and how to plan a release so review does not become a surprise at the end.
iPhone app development has its own expectations. Users know how a back swipe should feel, where the tab bar sits, how Dynamic Type scales text and what a share sheet looks like. An app that ignores those conventions feels foreign within seconds, even if every feature works. We design inside Apple's Human Interface Guidelines first and add brand character on top.
Going native on iOS also means direct access to what makes the platform worth building for: widgets on the home and lock screen, Live Activities, Apple Pay, HealthKit, Sign in with Apple, Core ML on device and tight integration with Apple Watch. If any of those sit at the heart of your product, a native Swift build is usually the right decision.
Native iOS is not the right fit for everyone. If most of your customers carry Android phones, or you need both stores on day one with a tight budget, a shared codebase may serve you better, and we will say so in the first call. For products where Apple users are the core audience, though, a well-built Swift app is hard to beat.
What we deliver
iOS App Development Services
From a first prototype to an app that keeps up with every new iOS release.
iPad app development
Layouts that use the larger screen properly, with sidebars, multiple columns, Split View and Stage Manager support. We add Apple Pencil input and keyboard shortcuts where they help real work.
Apple ecosystem extensions
Home and lock screen widgets with WidgetKit, Live Activities for orders and rides, App Clips, Siri Shortcuts and companion apps for Apple Watch.
Payments and subscriptions
StoreKit 2 for in-app purchases and subscriptions, and Apple Pay for physical goods and services. We plan which purchase path your product needs so it matches Apple's rules.
App Store submission
Screenshots, metadata, privacy labels, privacy manifests and review notes, handled by people who have done it many times. If Apple asks questions, we answer them.
Maintenance and iOS upgrades
Each June Apple announces a new iOS version and each fall it ships. We test against the betas so your app is ready when your users update.
Why SIZ Group
An iOS App Development Company That Knows Apple's Rules
Writing Swift is the easy part. The harder part is knowing how App Review reads a feature, when a digital purchase must go through In-App Purchase, what a privacy manifest has to declare, and how App Tracking Transparency affects your analytics plan. Our Swift developers bring that knowledge into scoping, before it becomes a rejection email.
We only hire the top 4% of developer applicants, and the team brings more than 10 years of collective experience. You work with the same small group from first call to launch, based in our Austin office.
Talk to us- SwiftUI first, UIKit where it countsSwiftUI speeds up most interfaces. We still reach for UIKit when a complex list, custom transition or older OS target demands it.
- Built for reviewLogin, payments, data collection and user content are designed to meet the App Review Guidelines from day one.
- Real devices in testingWe test across small and large iPhones and iPad sizes, not just the simulator, including VoiceOver and larger text settings.
- TestFlight from week oneYou install working builds on your own iPhone through TestFlight early and often, so feedback arrives while it is cheap to act on.
How we work
Our iOS Development Process
One team from first call to launch, with demos at every milestone.
01
Kickoff and iOS strategy
We agree which iPhone and iPad models and which minimum iOS version to support, since that choice shapes which frameworks we can use. We also flag any features that need special App Review attention.
02
Design in Apple's language
Screens are designed against the Human Interface Guidelines with SF Symbols, Dynamic Type and dark mode planned in. A clickable prototype lets you test flows before code.
03
Swift development
We build in Xcode with Swift concurrency, a clean data layer using SwiftData or Core Data where offline storage is needed, and a modular structure that stays easy to change. Builds reach your phone through TestFlight as features land.
04
Testing and tweaks
XCTest and UI tests cover the critical paths, and Instruments helps us find memory and battery problems. External TestFlight testers give real-world feedback before release.
05
App Store submission and support
We prepare the listing, privacy details and review notes, then submit and handle any questions from Apple. After launch we monitor crash reports and ship updates.
Tech stack
Our iOS Technology Stack
Apple's own tools first, with carefully chosen additions.
SwiftSwiftUIUIKitXcodeSwift ConcurrencySwiftDataCore DataStoreKit 2WidgetKitActivityKitHealthKitMapKitCore MLTestFlight
Who it's for
Where Native iOS Apps Pay Off
Health and fitness
HealthKit, Apple Watch and background workout tracking all favor native Swift. Our sports store design pairs gear shopping with fitness tracking.
Premium retail
Apple Pay, rich product imagery and smooth gestures matter when buyers are spending real money from their phones.
On-demand and delivery
Live Activities put a ride or delivery status on the lock screen and Dynamic Island, which suits our driver booking and grocery tracking designs.
Field and enterprise tools
iPad apps for inspections, sales and operations, with Apple Pencil input and offline storage for places with weak signal.
Pricing
What Shapes the Cost of an iOS App
The iOS-specific cost drivers are the minimum iOS version you support, the need for an iPad layout as well as iPhone, and how many Apple extensions you want. A widget, a Watch companion or a Live Activity is effectively a small extra app with its own testing.
Purchases add work. Subscriptions through StoreKit need server-side validation and restore flows, and a digital product that tries to avoid In-App Purchase can trigger review delays. Offline sync, custom animation and heavy media handling also add effort.
Mobile apps start at $4,500. Your final price depends on scope and is confirmed in writing after a free consultation, where we will also tell you whether an iPhone-only first release makes sense before you invest in iPad or Android.
Mobile apps start at
$4,500
Every project is scoped on a free call and confirmed in writing before work starts.
- Fixed scope and clear milestones
- Design, build, testing and launch
- Post-launch support available
Recent designs
All case studiesApps our team has designed
Why hire an iOS app development company instead of going cross-platform?+
Choose native iOS when your users are mostly on iPhone, when you need Apple features such as widgets, HealthKit or Apple Watch, or when interface polish is central to the product. If you need Android on day one and your app is mostly forms and lists, a shared codebase may be the better value.
Do you handle App Store submission?+
Yes. We prepare screenshots, descriptions, privacy labels and review notes, submit the build through App Store Connect and respond to any questions from App Review. If a build is rejected we fix the cause and resubmit.
Will my app work on iPad as well?+
iPhone apps can run on iPad, but they often look stretched or cramped. Proper iPad app development adapts layouts with size classes, adds multi-column views and supports multitasking. We scope that separately so you can decide when it is worth it.
Which iOS versions will you support?+
We usually target the current version and one or two before it, based on your audience. Supporting older versions limits which SwiftUI features we can use, so we agree the target during kickoff.
Can you take over an existing iOS app?+
Yes. We start with a code review to understand the architecture, dependencies and any outdated APIs, then propose a plan. Older Objective-C code can be maintained or moved to Swift step by step.
Do I need my own Apple Developer account?+
We recommend the app is published under your own organization's Apple Developer account so you own the listing, reviews and revenue. We help you set it up and add our team with the right access.
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Let's make it happen
Plan Your iPhone or iPad App With Us
Book a free consultation and get a clear scope for a native iOS build.