以下是2018年10月23日更新

經過大約一個月的時間的適配，專案正式使用XCode10(以下簡稱為10 or XC10)大部分庫都升級為Swift4.2（以下簡稱為 4.2 or S4.2），下面是適配過程中遇到的一些坑。

1. Swift4、Swift4.2混編

如果你對專案是小的獨立專案，完全可以全部升級為4.2，你可以略過第一條；如果你依賴了一些第三方的庫，且沒有升級4.2，你可以繼續看這一條。目前測試的結果來看，Swift4 和 S4.2的混編沒有什麼大的問題，如果你是通過cocoapod引入的可以在Podfile中加入如下程式碼：

swift_41_pod_targets = ['your_target_name']
post_install do |installer|
  installer.pods_project.targets.each do |target|
    if swift_41_pod_targets.include?(target.name)
      target.build_configurations.each do |config|
        config.build_settings['SWIFT_VERSION'] = '4.1'
      end
    end
  end
end
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2. NSDataAsset

升級XC10和S.2之前，專案裡面有些對 'NSDataAsset' 的錯誤使用：用‘NSDataAsset’讀ImageAsset中的圖片，這個是不正確的，但是卻可以工作，這次升級修復了這個BUG。

正確的做法使用'DataAsset'，然後才可以用‘NSDataAsset’讀取資料，我由於不夠認真且經驗不足還以為是個BUG，給Apple提了個BUG。。。[捂臉]

3. 第三方庫的重新命名 typealias

為了方便的適配S4.2對UIKit中的重新命名，有些第三方使用typealias對一些型別進行了重新命名，以 RxSwift 為例子，RxSwift中就有如下程式碼：

#if swift(>=4.2)
    public typealias UIControlEvents = UIControl.Event  private
#endif
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這會導致一些重新命名的型別即使不改也不會報錯，但是一旦去掉了對某個庫的依賴就會引入新的問題。

4.Delegate 的 Access Modifier

在升級S4.2過程中，XC偶爾會提示需要給某些Delegate方法新增 private修飾符，不要為了消除這個⚠️新增private，可能會導致Delegate永遠不被調到；另外，如果是一個public或者open的class，協議方法記得也要加上public，否則會出一樣的問題，具體原因我還在測試，但是現象是這樣的，有新的見解歡迎評論區討論。

5. 機型適配問題，iPhone XS Max字型變大

有些同事遇到XC9構建的安裝包在iPhone XS Max上會有字型變大的情況，這個貌似是普遍現象，微信也有，使用XC10構建安裝包可以解決這個問題，但是會遇到問題6

###6. iOS9.3以下系統Crash率飆升使用XC10構建安裝包可以解決問題5，但是iOS9.3以下的系統Crash到讓你懷疑人生

以下是2018年9月18日內容

AVAudioSession.sharedInstance().setCategory()

disappeared

Swift 4.2 中 iOS10以下不能用 AVAudioSession.sharedInstance() setCategory

可選方案:

使用OC實現該部分，然後使用Swift呼叫
放棄 iOS9使用者體驗

參考地址

do {
    if #available(iOS 11.0, *) {
        try audioSession.setCategory(.playback, mode: .default, policy: .longForm, options: [])
    } else if #available(iOS 10.0, *) {
        try audioSession.setCategory(.playback, mode: .default, options: [])
    } else {
        // Compiler error: 'setCategory' is unavailable in Swift
        try audioSession.setCategory(AVAudioSession.Category.playback)
    }
} catch let error {
    print("Unable to configure audio sesson category: \(error)")
}
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NSUnderlineStyle(.patternSolid、.none)

disappeared

可選方案:

.none

mutableAttributedString.addAttribute(NSAttributedString.Key.underlineStyle, value: NSUnderlineStyle.none.rawValue, range: range) ^~~~~ 'none' is unavailable: use [] to construct an empty option set

~~Wrong: mutableAttributedString.addAttribute(NSAttributedString.Key.underlineStyle, value: [], range: range)~~ Right: mutableAttributedString.addAttribute(NSAttributedString.Key.underlineStyle, value: 0, range: range)

使用 CTUnderlineStyleModifiers

// 沒有測試 NSUnderlineStyle.init(rawValue: Int(CTUnderlineStyleModifiers.patternSolid.rawValue))
使用其他預設值

下面是Rename操作

UIKit

#Swift4/UIKit

UITableViewCell

Swift 4	Swift 4.2
UITableViewCellStyle	UITableViewCell.CellStyle

UIEvent

Swift 4	Swift 4.2
UIEventSubtype	UIEvent.EventSubtype

UITableView

Swift 4	Swift 4.2
UITableViewScrollPosition	UITableView.ScrollPosition
UITableViewAutomaticDimension	UITableView.automaticDimension
UITableViewCellEditingStyle	UITableViewCell.EditingStyle
UITableViewRowAnimation	UITableView.RowAnimation
UITableViewStyle	UITableView.Style
UITableViewCellAccessoryType	UITableViewCell.AccessoryType

UIControl

Swift 4	Swift 4.2
UIControlEvents	UIControl.Event

UIWindow

Swift 4	Swift 4.2
UIWindowLevelAlert	UIWindow.Level.alert
UIKeyboardFrameEndUserInfoKey	UIResponder.keyboardFrameEndUserInfoKey
UIKeyboardFrameBeginUserInfoKey	UIResponder.keyboardFrameBeginUserInfoKey
UIKeyboardAnimationDurationUserInfoKey	UIResponder.keyboardAnimationDurationUserInfoKey
UIKeyboardAnimationCurveUserInfoKey	UIResponder.keyboardAnimationCurveUserInfoKey
UIKeyboardIsLocalUserInfoKey	UIResponder.keyboardIsLocalUserInfoKey
UIWindowDidBecomeVisible	UIWindow.didBecomeVisibleNotification
UIWindowDidBecomeHidden	UIWindow.didBecomeHiddenNotification
UIWindowDidBecomeKey	UIWindow.didBecomeKeyNotification
UIWindowDidResignKey	UIWindow.didResignKeyNotification
UIKeyboardWillShow	UIResponder.keyboardWillShowNotification
UIKeyboardDidShow	UIResponder.keyboardDidShowNotification
UIKeyboardWillHide	UIResponder.keyboardWillHideNotification
UIKeyboardDidHide	UIResponder.keyboardDidHideNotification

UIViewController

Swift 4	Swift 4.2
open func addChildViewController(_ childController: UIViewController)	open func addChild(_ childController: UIViewController)
open func willMove(toParentViewController parent: UIViewController?)	open func willMove(toParent parent: UIViewController?)
open func didMove(toParentViewController parent: UIViewController?)	open func didMove(toParent parent: UIViewController?)
open func removeFromParentViewController()	open func removeFromParent()

UIActivity

Swift 4	Swift 4.2
UIActivityType	UIActivity.ActivityType

UIActivityIndicatorView

Swift 4	Swift 4.2
activityIndicator.activityIndicatorViewStyle	activityIndicator.style

UIAlertController

Swift 4	Swift 4.2
UIAlertActionStyle	UIAlertAction.Style
UIAlertControllerStyle	UIAlertController.Style

UIPageViewController

Swift 4	Swift 4.2
UIPageViewControllerNavigationDirection	UIPageViewController.NavigationDirection
UIPageViewControllerSpineLocation	UIPageViewController.SpineLocation
UIPageViewControllerNavigationOrientation	UIPageViewController.NavigationOrientation
UIPageViewControllerTransitionStyle	UIPageViewController.TransitionStyle
UIPageViewControllerOptionsKey	UIPageViewController.OptionsKey

UINavigationController

Swift 4	Swift 4.2
UINavigationControllerOperation	UINavigationController.Operation

UIGestureRecognizer

Swift 4	Swift 4.2
UIGestureRecognizerStatePossible	UIGestureRecognizer.State.possible
UIGestureRecognizerStateBegan	UIGestureRecognizer.State.began
UIGestureRecognizerStateChanged	UIGestureRecognizer.State.changed
UIGestureRecognizerStateEnded	UIGestureRecognizer.State.ended
UIGestureRecognizerStateCancelled	UIGestureRecognizer.State.cancelled
UIGestureRecognizerStateFailed	UIGestureRecognizer.State.failed
UIGestureRecognizerStateRecognized	UIGestureRecognizer.State.recognized

NSLayoutFormat

Swift 4	Swift 4.2
NSLayoutFormatOptions	NSLayoutConstraint.FormatOptions

UIEdgeInsets

Swift 4	Swift 4.2
public func UIEdgeInsetsMake(_ top: CGFloat, _ left: CGFloat, _ bottom: CGFloat, _ right: CGFloat) -> UIEdgeInsets	UIEdgeInsets(top: CGFloat, left: CGFloat, bottom: CGFloat, right: CGFloat)
public func UIEdgeInsetsInsetRect(_ rect: CGRect, _ insets: UIEdgeInsets) -> CGRect	public func inset(by insets: UIEdgeInsets) -> CGRect

UIFontDescriptor

Swift 4	Swift 4.2
UIFontDescriptorSymbolicTraits	UIFontDescriptor.SymbolicTraits

UIImage

Swift 4	Swift 4.2
UIKIT_EXTERN NSData * __nullable `UIImagePNGRepresentation`(UIImage * __nonnull image);	public func `pngData()` -> Data?
NSData * __nullable `UIImageJPEGRepresentation`(UIImage * __nonnull image, CGFloat compressionQuality);	public func `jpegData`(compressionQuality: CGFloat) -> Data?

UIApplication

Swift 4	Swift 4.2
UIApplicationDidEnterBackground	UIApplication.didEnterBackgroundNotification
UIApplicationWillEnterForeground	UIApplication.willEnterForegroundNotification
UIApplicationDidFinishLaunching	UIApplication.didFinishLaunchingNotification
UIApplicationDidBecomeActive	UIApplication.didBecomeActiveNotification
UIApplicationWillResignActive	UIApplication.willResignActiveNotification
UIApplicationDidReceiveMemoryWarning	UIApplication.didReceiveMemoryWarningNotification
UIApplicationWillTerminate	UIApplication.willTerminateNotification
UIApplicationSignificantTimeChange	UIApplication.significantTimeChangeNotification
UIApplicationWillChangeStatusBarOrientation	UIApplication.willChangeStatusBarOrientationNotification
UIApplicationDidChangeStatusBarOrientation	UIApplication.didChangeStatusBarOrientationNotification
UIApplicationDidChangeStatusBarFrame	UIApplication.didChangeStatusBarFrameNotification
UIApplicationBackgroundRefreshStatusDidChange	UIApplication.backgroundRefreshStatusDidChangeNotification
UIApplicationProtectedDataWillBecomeUnavailable	UIApplication.protectedDataWillBecomeUnavailableNotification
UIApplicationProtectedDataDidBecomeAvailable	UIApplication.protectedDataDidBecomeAvailableNotification
UIApplicationUserDidTakeScreenshot	UIApplication.userDidTakeScreenshotNotification
UIApplicationOpenSettingsURLString	UIApplication.openSettingsURLString
UIApplicationLaunchOptionsKey	UIApplication.LaunchOptionsKey
UIInterfaceOrientationIsLandscape()	UIApplication.shared.statusBarOrientation.isLandscape

UIView

Swift 4	Swift 4.2
func `bringSubview`(toFront view: UIView)	func `bringSubviewToFront`(_ view: UIView)
UIViewAnimationOptions	UIView.AnimationOptions()

Foundation

NSAttributedString

Swift 4	Swift 4.2
NSAttributedStringKey	NSAttributedString.Key

QuartzCore

CAShapeLayer

Swift 4	Swift 4.2
kCALineCapRound	CAShapeLayerLineCap.round
kCALineCapButt	CAShapeLayerLineCap.butt
kCALineCapSquare	CAShapeLayerLineCap.square
kCALineJoinMiter	CAShapeLayerLineJoin.miter
kCALineJoinRound	CAShapeLayerLineJoin.round
kCALineJoinBevel	CAShapeLayerLineJoin.bevel
kCAFillRuleNonZero	CAShapeLayerFillRule.nonZero
kCAFillRuleEvenOdd	CAShapeLayerFillRule.evenOdd

參考資料

Swift-Migration-4.2

XCode10 swift4.2 適配遇到的坑

以下是2018年10月23日更新

1. Swift4、Swift4.2混編

2. NSDataAsset

3. 第三方庫的重新命名 typealias

4.Delegate 的 Access Modifier

5. 機型適配問題，iPhone XS Max字型變大

以下是2018年9月18日內容

AVAudioSession.sharedInstance().setCategory()

disappeared

可選方案:

NSUnderlineStyle(.patternSolid、.none)

disappeared

可選方案:

下面是Rename操作

UIKit

UITableViewCell

UIEvent

UITableView

UIControl

UIWindow

UIViewController

UIActivity

UIActivityIndicatorView

UIAlertController

UIPageViewController

UINavigationController

UIGestureRecognizer

NSLayoutFormat

UIEdgeInsets

UIFontDescriptor

UIImage

UIApplication

UIView

Foundation

NSAttributedString

QuartzCore

CAShapeLayer

參考資料

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