The following is updated on October 23, 2018

After about a month of adaptation, XCode10(hereinafter referred to as 10 or XC10) was officially used in the project. Most libraries were upgraded to Swift4.2 (hereinafter referred to as 4.2 or S4.2). Here are some problems encountered during the adaptation process.

1. Swift4 and Swift4.2

If you are working on a small, stand-alone project, you can upgrade to 4.2 altogether. You can skip section 1. If you rely on some third party library and have not upgraded 4.2, you can continue to see this article. So far the Swift4 and S4.2 combinations are working fine. If you’re using Cocoapod, you can add the following code to your Podfile:

swift_41_pod_targets = ['your_target_name']
post_install do |installer|
  installer.pods_project.targets.each do |target|
    ifswift_41_pod_targets.include? (target.name) target.build_configurations.eachdo |config|
        config.build_settings['SWIFT_VERSION'] = '4.1'
      end
    end
  end
end
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2. NSDataAsset

Before upgrading XC10 and S.2, there were some incorrect uses of ‘NSDataAsset’ in the project: using ‘NSDataAsset’ to read images in ImageAsset was incorrect, but it worked. This update fixes this BUG.

The right thing to do is to use ‘DataAsset’, and then you can use ‘NSDataAsset’ to read data. I thought it was a BUG due to my lack of care and experience, and I gave Apple a BUG… [his face]

3. Rename the third-party library TypeAlias

In order to easily adapt S4.2 to UIKit renaming, some third parties use TypeAlias to rename some types. For example, RxSwift has the following code:

# if swift (> = 4.2)
    public typealias UIControlEvents = UIControl.Event  private
#endif
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This can cause some renamed types to remain unchanged without error, but removing a dependency on a library can introduce new problems.

4. The Delegate Access Modifier

When upgrading S4.2, XC will occasionally prompt you to add private modifiers to some Delegate methods. Do not add private to eliminate this ⚠️, as it may cause the Delegate never to be called; In addition, if it is a public or open class, remember to add public to the protocol method, otherwise the same problem will occur. I am still testing the specific reason, but the phenomenon is like this, new insights welcome to discuss in the comments section.

5. IPhone XS Max font has become larger due to model adaptation problems

It seems to be a common phenomenon for some colleagues to encounter the font enlargement in the installation package built by XC9 on iPhone XS Max. Wechat also has this problem. Using XC10 to build the installation package can solve this problem, but there will be problem 6

Using XC10 to build installers can fix problem 5, but under iOS9.3 systems Crash enough to make you doubt your life

The following is from September 18, 2018

AVAudioSession.sharedInstance().setCategory()

disappeared

Swift iOS10 in 4.2 the following cannot use AVAudioSession. SharedInstance setCategory ()

Options:

• Implement this section using OC, and then use the Swift call
• Abandon the iOS9 user experience

Refer to the address

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)") }Copy the code

NSUnderlineStyle (patternSolid, none).

disappeared

Options:

• .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)

• Using CTUnderlineStyleModifiers

  / / no test NSUnderlineStyle. Init (rawValue: Int (CTUnderlineStyleModifiers. PatternSolid. RawValue))

• Use other defaults

The following is the Rename operation

UIKit

#Swift4/UIKit

UITableViewCell

UIEvent

UITableView

UIControl

UIWindow

UIViewController

UIActivity

UIActivityIndicatorView

UIAlertController

UIPageViewController

UINavigationController

UIGestureRecognizer

NSLayoutFormat

UIEdgeInsets

UIFontDescriptor

UIImage

UIApplication

UIView

Foundation

NSAttributedString

QuartzCore

CAShapeLayer

The resources

Swift – Migration – 4.2