WWDC 2025 - iOS 26's Revolutionary Multilingual Enhancements

The landscape of mobile application development has fundamentally shifted. We're no longer creating apps for a single market or language—we're building experiences that must seamlessly adapt to the diverse linguistic tapestry of our global user base. iOS 26 introduces groundbreaking features that transform how developers approach multilingual app development, moving beyond simple text translation to create genuinely inclusive user experiences.

The Multilingual Reality

In today's interconnected world, the majority of users are multilingual. A developer in Singapore might code primarily in English but consume content in Mandarin and Malay. A business professional in Beirut might use English for work applications while preferring Arabic for news and entertainment. This linguistic complexity presents both challenges and opportunities for iOS developers.

iOS 26 addresses this reality with three major innovations: Language Discovery, enhanced bidirectional text handling, and expanded calendar support. These features work together to create apps that feel native to users regardless of their linguistic preferences.

Language Discovery: Intelligent Preference Detection

The Traditional Challenge

Previously, users had to manually configure language preferences through the Settings app—a cumbersome process that many users never completed. This led to suboptimal experiences where users received content recommendations in languages they didn't prefer, despite their actual usage patterns indicating otherwise.

The iOS 26 Solution

Language Discovery leverages on-device intelligence to recognize user language patterns based on actual behavior: texting habits, content consumption, and browsing patterns. Siri can now intelligently suggest language configurations, offering to add bilingual keyboards or switch content recommendations to match detected language preferences.

For developers, this translates to the new Locale.preferredLocales API, which provides richer information than the traditional Locale.preferredLanguages:

// Legacy approach (being deprecated)
let preferredLanguages = Locale.preferredLanguages

// New iOS 26 approach
let preferredLocales = Locale.preferredLocales

Implementing Smart Language Prioritization

The real power of Language Discovery emerges when matching user preferences with your app's capabilities. Here's how to implement intelligent language prioritization:

let preferredLocales = Locale.preferredLocales

// Array of available Locale objects to translate from
let availableLocales = getAvailableLocalesForTranslatingFrom()

var matchedLocales: [Locale] = []

for locale in availableLocales {
    for preferredLocale in preferredLocales {
        if locale.language.isEquivalent(to: preferredLocale.language) {
            matchedLocales.append(locale)
            break
        }
    }
}

This approach allows apps like Translate to surface users' preferred languages at the top of selection lists, eliminating the need to scroll through dozens of options. Apple Music uses similar logic to recommend content and provide lyric translations in preferred languages.

Advanced Locale Handling

The new Locale objects provide access to rich metadata beyond simple language identifiers:

• Numbering systems for proper numeric formatting
• Localized string APIs for displaying language and region names
• Multiple identifier formats (BCP-47, ICU, CLDR) for different use cases
• Regional variations that affect spelling, date formats, and currency display

Natural Selection: Revolutionizing Bidirectional Text

Understanding the Complexity

Bidirectional text presents unique challenges that become evident during text selection. When combining left-to-right (LTR) and right-to-left (RTL) text, traditional selection mechanisms create awkward gaps because visual display order differs from storage order.

Consider selecting text that flows: "Hello שלום world" (where שלום is Hebrew for "hello"). Traditional selection would create visual gaps when dragging across language boundaries because the selection follows storage order rather than visual order.

Natural Selection Implementation

iOS 26 introduces Natural Selection, which allows selection to follow the visual cursor movement rather than storage order. This requires a fundamental shift from single-range to multi-range selection:

// iOS 18 approach (single range)
let selectedRange = textView.selectedRange

// iOS 26 approach (multiple ranges)
let selectedRanges = textView.selectedRanges

Practical Implementation Considerations

When implementing features that modify selected text, developers must account for non-contiguous ranges:

let ranges = textView.selectedRanges.reversed()
for range in ranges {
    textView.textStorage.deleteCharacters(in: range)
}

Note the use of reversed() to process ranges from end to beginning, preventing index invalidation as text is deleted.

TextKit2 Requirements

Natural Selection requires TextKit2. While UITextView and UITextField use TextKit2 by default in iOS 26, accessing textView.layoutManager reverts to TextKit1, disabling Natural Selection. Use textView.textLayoutManager instead to maintain TextKit2 functionality.

Dynamic Writing Direction

iOS 26 introduces intelligent writing direction detection that adapts based on content. Rather than fixing writing direction based on the first character, the system now evaluates the entire text context to determine the most appropriate direction. This creates more natural experiences when users switch between languages within a single text input.

Enhanced Calendar Support

The internationalization improvements extend to calendar systems with 11 new calendar identifiers added to the existing 16 options. New support includes Gujarati, Marathi, and Korean calendars, accessible through Calendar.Identifier in the Foundation framework.

This expansion allows apps to display dates, months, and calendar events in culturally appropriate formats, enhancing user experience for communities that use alternative calendar systems.

Delegate Protocol Updates

iOS 26 updates UITextView delegate protocols to support multi-range operations:

• shouldChangeTextInRanges replaces single-range text change validation
• editMenuForTextInRange now accepts multiple ranges for contextually appropriate menu options

These updates ensure that delegate implementations properly handle the new multi-range selection paradigm.

Best Practices for Implementation

Preparation Strategy

Start with internationalization fundamentals using Xcode's localization tools, Foundation APIs, and Unicode support. This preparation enables easy addition of new languages without architectural changes.

TextKit2 Adoption

Fully embrace TextKit2 for complex script handling and advanced layout control. The framework seamlessly manages bidirectional text while providing granular control over typography and layout.

Formatter Usage

Leverage Swift's formatting APIs for automatic adaptation of dates, numbers, and currency to user preferences. These formatters eliminate the need for custom locale-specific logic.

Input Method Optimization

Utilize iOS 26's enhanced keyboard features, including the new Arabizi transliteration keyboard, bilingual suggestions, and multi-script keyboards. Configure inputAccessoryView and textInputContextIdentifier to enhance the input experience.

Looking Forward

These iOS 26 enhancements represent a significant evolution in multilingual app development. Language Discovery eliminates configuration friction, Natural Selection solves long-standing bidirectional text challenges, and expanded calendar support acknowledges global diversity.

The shift from Locale.preferredLanguages to Locale.preferredLocales signals Apple's commitment to richer internationalization support. While the former may be deprecated in future releases, early adoption of the new APIs positions apps for continued compatibility and enhanced functionality.