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SwiftUI vs UIKit
Quick answer
Most new iPhone apps should start with SwiftUI and use UIKit only for screens that need finer control. The two can work together in one app. An existing UIKit app rarely needs a full rewrite. Add SwiftUI screens gradually instead. Set your oldest supported iOS version first, since it limits newer SwiftUI features.
If you're having an iPhone app built, your developers may ask whether to use SwiftUI or UIKit. Both are Apple's tools for building the screens people tap. The choice affects build speed, future changes and who can work on the app. You don't need to code to decide well, but you should know the trade-offs.
Key Takeaways
- UIKit is Apple's original framework for iPhone app screens, used since 2008.
- SwiftUI, introduced in 2019, builds screens with less code and works across Apple devices.
- Most new apps start with SwiftUI and use UIKit where it fits better.
- SwiftUI and UIKit can be mixed in the same app.
- Existing UIKit apps can add SwiftUI screens gradually instead of a full rewrite.
- The oldest iOS version you support affects which SwiftUI features you can use.
Published: October 27, 2026 | Reading Time: ~8 minutes | Category: Swift Development
This guide explains SwiftUI and UIKit for business owners: what each is, where each fits, mixing both, older iOS versions, existing apps, hiring, cost and maintenance. Put plainly: build new screens in SwiftUI, keep UIKit where it still earns its place and mix them when needed.
In This Playbook
- What UIKit is
- What SwiftUI is
- Where each fits
- Mixing both
- Older iOS versions
- Existing UIKit apps
- Hiring
- Cost and speed
- Native or not?
- Questions to ask your developers
- What to measure
- The first three months
What UIKit is
Apple's original framework. Used since the first iPhone software kit in 2008.
Mature and proven. Many large apps are built with it.
Fine control. Detailed control over every part of a screen.
More code. Screens usually take longer to build and change.
What SwiftUI is
Apple's newer framework. Introduced in 2019.
Less code. Screens are described in a simpler way.
Faster to build and change. Especially for standard screens.
Works across Apple devices. iPhone, iPad, Mac and Apple Watch, as in fitness Swift apps.
Where each fits
SwiftUI. New apps, standard screens, forms, settings and apps for several Apple devices, such as a tenant app.
UIKit. Highly custom screens, some complex lists and features that need fine control.
Both. Many apps use SwiftUI for most screens and UIKit for a few.
Mixing both
One app, two frameworks. Apple lets SwiftUI and UIKit screens work together.
Use the right tool per screen. No need to choose one for everything.
A common pattern. SwiftUI by default, UIKit for special cases.
Older iOS versions
Features depend on the iOS version. Newer SwiftUI features need newer iOS.
Know your users. Check which iOS versions your customers run.
Plan the minimum version. Supporting very old versions limits SwiftUI options.
Yearly updates. As covered in Swift app maintenance and iOS updates.
Existing UIKit apps
Don't rewrite everything. A full rewrite is costly and risky.
Add SwiftUI gradually. New screens and redesigned sections first.
Rewrite only with a reason. Such as a major redesign, as weighed in redesign vs rebuild.
Hiring
Most iOS developers know both. Newer developers often start with SwiftUI.
Large UIKit codebases. Need developers comfortable with it.
Ask vendors. Which they use and why.
Cost and speed
SwiftUI often builds faster. Fewer lines for standard screens.
Custom work costs more either way. Complex screens take time in both.
Long-term cost. Easier changes later reduce maintenance costs.
The native case is weighed in making the business case for native iOS.
Native or not?
SwiftUI and UIKit are both native. They build iPhone apps directly.
Cross-platform tools differ. As weighed in native, cross-platform or web.
Questions to ask your developers
Which framework for each part of the app, and why?
What's the minimum iOS version, and what does it limit?
For existing apps, what's the plan for adding SwiftUI?
How will choices affect cost and future changes?
What to measure
Build time. For new screens.
Change time. How long updates take.
Crash-free users. After each release.
iOS version coverage. Share of customers supported.
Maintenance cost. Per year.
The first three months
Days 1–30: decide
Check which iOS versions your customers use, set the minimum version and agree on SwiftUI by default with UIKit for special cases.
Days 31–60: build
Build new screens in SwiftUI, keep or add UIKit where it fits and test across supported iOS versions.
Days 61–90: review
Compare build and change times, check crash reports and plan gradual SwiftUI adoption for older parts of the app.
How Astra chooses between SwiftUI and UIKit
Astra Results Marketing builds native iPhone apps with the right framework for each screen. We use SwiftUI by default, UIKit where it fits better, mix them when needed and plan minimum iOS versions around your customers.
For existing apps, we add SwiftUI gradually rather than rewriting. Engagements begin with an app review through our Swift app development team.
Related reading
Frequently asked questions
What's the difference between SwiftUI and UIKit?
Both build iPhone app screens. UIKit is Apple's original framework with fine control; SwiftUI is newer, needs less code and works across Apple devices.
Which should a new app use?
Usually SwiftUI by default, with UIKit for screens that need special control.
Can an app use both?
Yes. SwiftUI and UIKit screens can work together in the same app.
Should we rewrite our UIKit app in SwiftUI?
Usually not all at once. Add SwiftUI gradually for new and redesigned screens.
Does SwiftUI work on older iPhones?
It depends on the iOS version. Newer SwiftUI features need newer iOS, so set your minimum version based on your customers.
Is SwiftUI cheaper?
It often builds standard screens faster, which can lower cost. Complex custom screens take time in either framework.
Ready to build your iPhone app with the right tools? Astra Results Marketing builds native apps with SwiftUI by default and UIKit where it fits, plans iOS versions around your customers and modernizes existing apps gradually. ▸ CALL (786) 321-2866 · ▸ REQUEST YOUR CONSULTATION
