将开发环境升级到Xcode 10, Swift 4.2及iOS 12后，工程里会出现许多错误。其中的很多错误，只需要点击它的小圆点，Xcode会自动帮我们修复，这些略去不谈。本文主要讲一下不能自动修复的错误。
- GRDB.swift使用Carthage编译错误。
GRDB.swift本身不支持使用Carthage集成，在Xcode 9时可以成功集成，但升级后就不可以了，并且官方不提供技术支持，参见：https://github.com/groue/GRDB.swift/issues/417
当必须要使用Carthage和GRDB时，只能手动集成GRDB了。
1）首先去https://github.com/groue/GRDB.swift/releases， 下载最新版的发布版
2）然后打开GRDB工程，编译出模拟器版和设备版的库
3）将这两个库合并成一个universal framework，具体来说可以使用
lipo -create -output ./c/GRDB ./a/GRDB.framework/GRDB ./b/GRDB.framework/GRDB
cp -R ./a/GRDB.framework ./c/GRDB.framework
mv ./c/GRDB ./c/GRDB.framework/GRDB
最后，将目录b中的GRDB.framework/Modules/GRDB.swiftmodule中的所有内容复制到目录c中的对应位置。当前目录c中的GRDB.framework就是我们所需要的。
4）打包时不支持包含i386或者x86_64架构的包内容，所以还需要将它们去掉。这里使用的是如下脚本，是根据云信的脚本修改的（它的脚本在Xcode 10下不能正确工作）。
strip_invalid_archs() {
binary="$1"
echo "current binary ${binary}"
echo "$(lipo -info "$binary")"
# Get architectures for current file
archs="$(lipo -info "$binary" | rev | cut -d ':' -f1 | rev)"
isDevice=true
for arch in $ARCHS; do
if [ ${arch} == "i386" ]; then
echo "i386"
isDevice=false
break
fi
if [ ${arch} == "x86_64" ]; then
echo "x86_64"
isDevice=false
break
fi
if [ ${arch} == "armv7" ]; then
echo "armv7"
break
fi
if [ ${arch} == "arm64" ]; then
echo "arm64"
break
fi
done
for arch in $archs; do
if [ ${isDevice} == true ]; then
if [ ${arch} == "i386" ]; then
lipo -remove i386 -output "$binary" "$binary" || exit 1
echo "Stripped $binary of architectures:$arch"
fi
if [ ${arch} == "x86_64" ]; then
lipo -remove x86_64 -output "$binary" "$binary" || exit 1
echo "Stripped $binary of architectures:$arch"
fi
else
if [ ${arch} == "armv7" ]; then
lipo -remove armv7 -output "$binary" "$binary" || exit 1
echo "Stripped $binary of architectures:$arch"
fi
if [ ${arch} == "arm64" ]; then
lipo -remove arm64 -output "$binary" "$binary" || exit 1
echo "Stripped $binary of architectures:$arch"
fi
fi
done
}
APP_PATH="${TARGET_BUILD_DIR}/${WRAPPER_NAME}"
# This script loops through the frameworks embedded in the application and
# removes unused architectures.
find "$APP_PATH" -name '*.framework' -type d | while read -r FRAMEWORK
do
FRAMEWORK_EXECUTABLE_NAME=$(defaults read "$FRAMEWORK/Info.plist" CFBundleExecutable)
FRAMEWORK_EXECUTABLE_PATH="$FRAMEWORK/$FRAMEWORK_EXECUTABLE_NAME"
echo "Executable is $FRAMEWORK_EXECUTABLE_PATH"
strip_invalid_archs "$FRAMEWORK_EXECUTABLE_PATH"
done
这样就完成了，最后提供一下参考的云信的脚本：
https://dev.yunxin.163.com/docs/product/IM%E5%8D%B3%E6%97%B6%E9%80%9A%E8%AE%AF/SDK%E5%BC%80%E5%8F%91%E9%9B%86%E6%88%90/iOS%E5%BC%80%E5%8F%91%E9%9B%86%E6%88%90/%E9%9B%86%E6%88%90%E6%96%B9%E5%BC%8F
- 错误：UIEdgeInsetsInsetRect' has been replaced by instance method 'CGRect.inset(by:)
比如之前是：
UIEdgeInsetsInsetRect(bounds, UIEdgeInsets(top: padding, left: padding, bottom: padding, right: padding))
修改为：
bounds.inset(by: UIEdgeInsets(top: padding, left: padding, bottom: padding, right: padding)）
- 错误：Method does not override any method from its superclass
有以下两个函数会报这个错：
override func childViewControllerForHomeIndicatorAutoHidden() -> UIViewController?
override func prefersHomeIndicatorAutoHidden() -> Bool
这是因为它们在Swift 4.2中被改成变量了，改成下面这样：
override var childForHomeIndicatorAutoHidden: UIViewController?
override var prefersHomeIndicatorAutoHidden: Bool
- 类型要求更加严格
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any])
以前工程里是这样写的，但现在不行了，必须写成
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any])
- 错误：'UIImageJPEGRepresentation' has been replaced by instance method 'UIImage.jpegData(compressionQuality:)'
将代码
UIImageJPEGRepresentation(image, quality)
改成
image.jpegData(compressionQuality: quality)
- 错误：AVAudioSession， 'setCategory' is unavailable in Swift
这是Swift 4.2的一个bug，AVAudioSession的setCategory这个函数提供了一个新版本，然后旧版本被删了。导致iOS 10以下的版本没有办法设置category。好在Objective-C版本的函数还能用，有2种方案，详见参考链接，我使用了简单的那一种，如下：
AVAudioSession.sharedInstance().perform(NSSelectorFromString("setCategory:error:"), with: AVAudioSession.Category.playback)
参考：https://stackoverflow.com/questions/52413107/avaudiosession-setcategory-swift-4-2
- Xcode 10提交的App在iOS 9.0 ~ iOS 9.2版本手机上随机crash
这是Xcode 10的一个know issue:
Apps that contain asset catalogs built using Xcode 10 or later with a deployment target set to iOS 9.0, 9.1 or 9.2 produce content incompatible with the runtimes of those iOS versions. (44535967, 45723580, 45723189)
原文参见：https://developer.apple.com/documentation/xcode_release_notes/xcode_10_1_release_notes?preferredLanguage=occ
那么解决方案有两个：
a. 使用Xcode 9.4.1打包提交App
b. 将可支持的最低iOS版本提到iOS 9.3
参考：
https://stackoverflow.com/questions/52364231/our-app-crashed-in-ios-9-which-upload-by-xcode-10
