iOS App Design

Unlike Android, Apple's iOS is a proprietary mobile operating system that can only be installed on iPhone, iPad, and other Apple mobile devices. However, it offers developers several open-source libraries, resources, and components.

Its free software development kit (SDK) gives developers access to various functions and services of iOS devices. It also features an iPhone simulator that allows app developers to recreate the appearance and feel of the device on their computers when developing an app. The iOS SDK helps developers create iOS apps with officially supported programming languages, including Swift and Objective-C. However, you can also use other programming languages to develop native iOS applications.

Due to the ownership of its ecosystem, iOS is one of the most secure operating systems. Simply put, other companies or developers can't fully access the source code. Additionally, all Apple components, especially open-source ones, are regularly checked for compliance with security requirements. This is one of the reasons developers often struggle to meet Apple's requirements when placing their apps in the Apple store. If something seems suspicious, Apple reserves the right to block apps immediately.

iOS devices have different layers that contain unique components responsible for performing specific functions within the application, guaranteeing efficient and safe communication with the device's hardware.

These include:

• The Cocoa Touch layer (or the application layer) is responsible for the application's appearance and how it interacts with users. Plus, it also contains critical iOS components that allow multitasking between applications and using the touchscreen to request commands.
• The Media layer holds all video, audio, and graphic frameworks that allow users to listen to their favorite music or watch movies.
• The Core Services layer contains essential technologies like: the Address book framework, Core Location framework, Social framework, Healthkit framework, and others. These are necessary to support device applications. It doesn't mean your application will need all these components but they are available to be accessed at any time.
• The Core Layer is the closest one to the device hardware. It handles low-level functionalities such as networking, memory, and external accessories.

Due to the layered structure, iOS applications keep functioning effortlessly even if there are certain hardware changes on the device. Plus, the malfunctioning of one layer doesn't affect others, which makes it easier to test and debug each layer.

Unlike Android, iOS users traditionally had limited options for customizing their home screen. With iOS 14, users gained the ability to create custom app icons using the Shortcuts app and add widgets. Since iOS 15, they can also hide or show specific home screens based on Focus modes, which can change depending on location or time of day. However, iOS still maintains a consistent visual design across devices, without allowing changes to system-wide typefaces, colors, or other interface elements. While this limits personalization, it ensures a uniform experience and avoids overwhelming users with too many choices.

Beyond the home screen, iOS users can customize the Control Center, switch between light and dark modes, set default apps for web browsing and email, manage notifications, set time limits, block specific contacts, and organize app icons and widgets to create custom layouts. Users can also apply light, dark, or custom tints to elements for a more personalized look. Newer iOS versions support installing third-party typefaces through various apps. However, these fonts only work within supported applications like Pages or Photoshop — Apple does not allow changing the system-wide typeface.

One of the most fantastic advantages of Apple products is their continuity — a seamlessly integrated environment between all your devices (iPhone, Apple Watch, AirPods, Mac) using Apple-only features like iCloud, Apple Pay, AirDrop, or Handoff.

Using iOS integration technology, users can:

• Wirelessly send photos, files, websites, and videos to a nearby Apple device
• Start working on one device and then resume their work on a nearby device without any delays
• Copy content on one Apple device and paste it on another Apple device^[1]
• Pay with their iPhone or Apple Watch when shopping online on Mac
• Receive phone calls and SMS on their Mac, share an Internet connection between devices, and do many other activities seamlessly^[2]

Due to this well-developed integration within the iOS environment, mobile designers and developers have more flexibility with the app's functionality. For example, a mobile fitness app that tracks running, cycling, and walking is most beneficial when downloaded on a user's Apple Watch. Integrated with the iPhone's Health app, it can share users' progress, distance, steps, or duration and receive optimized activity analysis and health recommendations.

Primary navigation in iOS apps guides users to main destinations through a tab bar positioned at the bottom of the screen. This fundamental navigation pattern ensures immediate access to core app features while maintaining consistency with platform conventions.

On iOS, the primary navigation bar is typically placed at the bottom of the screen and contains up to 5 tabs, each with an icon and a label. While many apps reserve the center tab for key actions like creating content or initiating messages, others use this prominent position for their most frequently accessed feature.

Common navigation patterns include Home for main content, Search for discovery, Library or Profile for personal content, and Settings for app configuration. Apps should prioritize these destinations based on user behavior and feature importance rather than following rigid placement rules.

The floating action button (FAB) is a well-known primary action button on Android devices. It is commonly placed at the bottom center or bottom right of the screen, appearing above other UI elements. Google’s Material Design guidelines recommend this placement to keep the FAB easily accessible while maintaining a clean interface.

In contrast, iOS does not have a direct FAB equivalent. Instead, primary actions are often placed in the upper right corner of the navigation bar (e.g., a "Compose" button in Mail or a "New Chat" button in Messages). Depending on the app’s design, primary actions may also appear in toolbars, action sheets, or as large buttons within the content area. Mobile developers sometimes experiment with button placement, such as integrating primary action buttons into a bottom navigation bar.

For iOS, Apple’s Human Interface Guidelines recommend a minimum tap target size of 44x44pt.^[3] This applies to interactive elements like buttons, links, and icons, ensuring they are large enough to be tapped comfortably without accidental taps on nearby elements.

This size requirement ensures that users, including those with larger fingers or other accessibility needs, can interact with the app efficiently. It’s important to note that this is a minimum size, and increasing the tap target size can improve usability, especially in cases where the user interface is dense or includes many small controls.

There are 4 different ways to navigate back on iOS applications:

• Tapping the Back button on the top-left of the screen. It usually contains the name of the previous page or section and a chevron pointing to the left.
• Swiping right from the left edge of the screen. Users can apply this action where the Back button is present.
• Pressing the Done or Cancel button. This is usually placed on the top-right corner of the modal view.
• Swiping down on content placed within a modal or fullscreen view. Fullscreen views are usually used for displaying photos or videos that take up the entire screen.

Action menus slide up from the bottom of the screen when users press a button or attempt to take action. They have an excellent location within thumb-reach and are meant to present the most common, high-value tasks.

Additionally, there are context menus that appear after long-pressing the element, blurring out the background. The main drawback of context menus is that there's no visual indication of their existence until they're activated.

Mobile developers often experiment with the menus' appearance, placement, and behavior. However, using native action menus is more beneficial for users as they experience less cognitive load and don't need to learn new patterns.

In iOS, segmented controls provide a horizontal set of mutually exclusive options that switch between different views of the same content. Unlike traditional tabs, these controls are designed for filtering or changing views within the same context, not for navigating to different app sections.

The Health app demonstrates this pattern effectively in its activity tracking views. When viewing daily steps, the segmented control offers views like "Day," "Week," "Month," and "Year" — different presentations of the same step data. Users can switch between these views to analyze their walking patterns over different time periods while staying within the steps-tracking context.

Similarly, heart rate monitoring in the Health app uses segmented controls to switch between views showing "Latest Reading," "Daily Average," and "Heart Rate Variability." These segments represent different aspects of the same heart rate data rather than navigating to unrelated health metrics.

San Francisco and New York are the default typefaces on iOS devices. San Francisco is a neo-grotesque sans-serif typeface that most people associate with Apple products. With the release of iOS 14, designers can combine different font styles of the default typefaces to create a more robust visual hierarchy or to highlight semantic differences in content.

Can you apply custom typefaces in your apps when designing for iOS? Certainly, but they should be legible enough and used only if you want to highlight your brand or create a unique gaming experience. iOS guidelines also recommend using custom fonts for display text only and sticking to system fonts for reading or interface text.^[4]