XCode10 swift4.2 适配遇到的坑

以下是2018年10月23日更新

经过大约一个月的时间的适配，项目正式使用XCode10(以下简称为10 or XC10)大部分库都升级为Swift4.2（以下简称为 4.2 or S4.2），下面是适配过程中遇到的一些坑。

1. Swift4、Swift4.2混编

如果你对项目是小的独立项目，完全可以全部升级为4.2，你可以略过第一条；如果你依赖了一些第三方的库，且没有升级4.2，你可以继续看这一条。目前测试的结果来看，Swift4 和 S4.2的混编没有什么大的问题，如果你是通过cocoapod引入的可以在Podfile中加入如下代码：

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

2. NSDataAsset

升级XC10和S.2之前，项目里面有些对 'NSDataAsset' 的错误使用： 用‘NSDataAsset’读ImageAsset中的图片，这个是不正确的，但是却可以工作，这次升级修复了这个BUG。

正确的做法使用'DataAsset'，然后才可以用‘NSDataAsset’读取数据，我由于不够认真且经验不足还以为是个BUG，给Apple提了个BUG。。。[捂脸]

3. 第三方库的重命名 typealias

为了方便的适配S4.2对UIKit中的重命名，有些第三方使用typealias对一些类型进行了重命名，以 RxSwift 为例子，RxSwift中就有如下代码：

#if swift(>=4.2)
    public typealias UIControlEvents = UIControl.Event  private
#endif

这会导致一些重命名的类型即使不改也不会报错，但是一旦去掉了对某个库的依赖就会引入新的问题。

4.Delegate 的 Access Modifier

在升级S4.2过程中，XC偶尔会提示需要给某些Delegate方法添加 private修饰符，不要为了消除这个⚠️添加private，可能会导致Delegate永远不被调到；另外，如果是一个public或者open的class，协议方法记得也要加上public，否则会出一样的问题，具体原因我还在测试，但是现象是这样的，有新的见解欢迎评论区讨论。

5. 机型适配问题，iPhone XS Max字体变大

有些同事遇到XC9构建的安装包在iPhone XS Max上会有字体变大的情况，这个貌似是普遍现象，微信也有，使用XC10构建安装包可以解决这个问题，但是会遇到问题6

6. iOS9.3以下系统Crash率飙升

使用XC10构建安装包可以解决问题5，但是iOS9.3以下的系统Crash到让你怀疑人生

以下是2018年9月18日内容

AVAudioSession.sharedInstance().setCategory()

disappeared

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

可选方案:

• 使用OC实现该部分，然后使用Swift调用
• 放弃 iOS9用户体验

参考地址

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)")
}

NSUnderlineStyle(.patternSolid、.none)

disappeared

可选方案:

• .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

  // 没有测试
  NSUnderlineStyle.init(rawValue: Int(CTUnderlineStyleModifiers.patternSolid.rawValue))

• 使用其他默认值

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

参考资料

Swift-Migration-4.2