README.md

SizeClassDemo

參考 raywenderlich： adaptive-layout-tutorial-ios-11-getting-started 教學，但完全使用程式碼實現。

實作方式

新增三個 Constrains 實作及適當時機切換

• sharedConstraints
• regularConstraints
• compactConstraints

注意事項

- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection 第一次 horizontalSizeClass、verticalSizeClass 會取得 UIUserInterfaceSizeClassUnspecified，這部分需要另外判斷； 這邊直接透過 [UIScreen mainScreen].bounds 去判斷長寬比去決定實作的 Constraints。

self.traitCollection 跟 previousTraitCollection 相反

為什麼不用 Visual Format Language? 主要是因為再 xcode 9, iOS 11 有點問題，參考資訊如下： https://stackoverflow.com/questions/46576358/uiscrollview-not-scrolling-in-ios11

參考資料

Default Size Classes for Different Devices

Each iOS device has a default set of size classes that you can use as a guide when designing your interface. Table 12-2 lists the size classes for devices in both portrait and landscape orientations. Devices not listed in the table have the same size classes as the device with the same screen dimensions.

Table 12-2 Size classes for devices with different screen sizes.

Device	Portrait	Landscape
iPad (all) iPad Mini	Vertical size class: Regular Horizontal size class: Regular	Vertical size class: Regular Horizontal size class: Regular
iPhone 6 Plus	Vertical size class: Regular Horizontal size class: Compact	Vertical size class: Compact Horizontal size class: Regular
iPhone 6	Vertical size class: Regular Horizontal size class: Compact	Vertical size class: Compact Horizontal size class: Compact
iPhone 5s iPhone 5c iPhone 5	Vertical size class: Regular Horizontal size class: Compact	Vertical size class: Compact Horizontal size class: Compact
iPhone 4s	Vertical size class: Regular Horizontal size class: Compact	Vertical size class: Compact Horizontal size class: Compact

IMPORTANT

Never assume that your app will be displayed with a specific size class on a device. Always check the size class found in an object’s trait collection when making decisions about how to configure that object.

參考連結

Apple Official Document