Accessibility
iOS offers extensive accessibility features for users with vision loss, hearing loss, and other disabilities. Most UIKit-based apps can be made accessible with very little effort, allowing more people to use your app while providing an equally engaging experience for all.
iOS為用戶提供大量可訪問性的特性，如失明，失聰，或者其他殘疾。大部分基于UIKit的app用少量的努力就能支持可訪問性，當你為所有人提供同樣迷人的體驗時，會有更多用戶愿意用你的app
Provide alternative text labels for images, icons, and interface elements.Alternative text labels aren’t visible onscreen, but they let VoiceOver audibly describe what's onscreen, making navigation easier for people with visual impairments.
為圖片，圖標，界面元素提供可選的文本標簽。可選的文本標簽在屏幕上不是可見的，但是讓它們可聽見從而知道什么在屏幕上，對于有視覺障礙的人是更好的導航。
Respond to accessibility preferences.If your app uses UIKit to implement its user interface, text and interface elements automatically adapt to certain accessibility preferences, such as bold and larger text. Your app should also check and respond to accessibility preferences when appropriate, such as when the option to reduce motion is enabled. Apps implementing custom fonts should attempt to match the accessibility behavior of the system fonts.
對可訪問性偏好應答。如果你的app用UIKit來實現用戶界面，文本和界面元素自動適應某一可訪問性偏好，例如加粗或更大的文本。你的app應該也適當地檢測和應答可訪問性偏好，例如激動減少動作選項時。Apps實現自定義字體應該嘗試匹配系統字體的可訪問性。
Test your app with accessibility features.In addition to text and motion changes, accessibility options can change contrast, invert colors, reduce transparency, and more. Enable these settings and observe how your app will look and behave for people who enable these features.
測試你的app的可訪問性特性。除了文本和動作的改變，可訪問性選項還可以改變對比，調整顏色，減少透明度，及其他。激活這些設置然后作為用戶觀察你的app外觀和行為。
Include closed captions and audio descriptions.Closed captions allow the deaf and hard-of-hearing to perceive spoken dialogue and other audible content in videos. Audio descriptions provide spoken narration of important video content for the visually impaired.
加入字幕和語音描述。字幕讓聾子和聽力障礙的人理解在視頻文件中的口語對話和其他語音內容。語音描述為那些有視覺障礙的人提供重要視頻文件內容的口語描述。
For more information, seeiOS AccessibilityandAccessibility?Programming?Guide for iOS.
https://developer.apple.com/ios/human-interface-guidelines/interaction/accessibility/
