Xcode 8 beta 6：main.swift 不会编译
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Xcode 8 beta 6: main.swift won't compile
提问by Jason Hocker
We have a custom UIApplication object, so our main.swift was
我们有一个自定义的 UIApplication 对象，所以我们的 main.swift 是
import Foundation
import UIKit
UIApplicationMain(Process.argc, Process.unsafeArgv, NSStringFromClass(MobileUIApplication), NSStringFromClass(AppDelegate))
and that didn't work in Xcode 8 beta 5 so we used this
这在 Xcode 8 beta 5 中不起作用，所以我们使用了这个
//TODO Swift 3 workaround? https://forums.developer.apple.com/thread/46405
UIApplicationMain( Process.argc, UnsafeMutablePointer<UnsafeMutablePointer<CChar>>(Process.unsafeArgv), nil, NSStringFromClass(AppDelegate.self))
On Xcode 8 beta 6 we get Use of unresolved identifier 'Process'
在 Xcode 8 beta 6 上我们得到Use of unresolved identifier 'Process'
What do we need to do in Xcode 8 beta 6/Swift 3 to define the UIApplicationMain?
我们需要在 Xcode 8 beta 6/Swift 3 中做什么来定义 UIApplicationMain？
回答by matt
I write it this way:
我是这样写的：
UIApplicationMain(
CommandLine.argc,
UnsafeMutableRawPointer(CommandLine.unsafeArgv)
.bindMemory(
to: UnsafeMutablePointer<Int8>.self,
capacity: Int(CommandLine.argc)),
nil,
NSStringFromClass(AppDelegate.self)
)
To change the UIApplication class, substitute NSStringFromClass(MobileUIApplication.self)for nilin that formulation.
要改变UIApplication类，替代NSStringFromClass(MobileUIApplication.self)了nil该配方。
However, if your onlypurpose here is to substitute a UIApplication subclass as the shared application instance, there's an easier way: in the Info.plist, add the "Principal class" key and set its value to the string name of your UIApplication subclass, and mark your declaration of that subclass with an @objc(...)attribute giving it the same Objective-C name.
但是，如果您在这里的唯一目的是将 UIApplication 子类替换为共享应用程序实例，则有一种更简单的方法：在Info.plist 中，添加“Principal class”键并将其值设置为您的 UIApplication 子类的字符串名称，并使用一个@objc(...)属性标记该子类的声明，并为其提供相同的 Objective-C 名称。
EDITThis problem is now solved in Swift 4.2. CommandLine.unsafeArgvnow has the correct signature, and one can call UIApplicationMaineasily:
编辑这个问题现在在 Swift 4.2 中得到解决。CommandLine.unsafeArgv现在有正确的签名，可以UIApplicationMain轻松调用：
UIApplicationMain(
CommandLine.argc, CommandLine.unsafeArgv,
nil, NSStringFromClass(AppDelegate.self)
)
回答by OOPer
It seems Processhas been renamed to CommandLinein beta 6.
它似乎Process已CommandLine在 beta 6 中重命名为。
But the type of CommandLine.unsafeArgvis mismatching the second argument of UIApplication, so you may need to write something like this:
但是 的类型与CommandLine.unsafeArgv的第二个参数不匹配UIApplication，因此您可能需要编写如下内容：
CommandLine.unsafeArgv.withMemoryRebound(to: UnsafeMutablePointer<Int8>.self, capacity: Int(CommandLine.argc)) {argv in
_ = UIApplicationMain(CommandLine.argc, argv, NSStringFromClass(MobileUIApplication.self), NSStringFromClass(AppDelegate.self))
}
(UPDATE)This mismatching should be considered as a bug. Generally, you'd better send a bug reportwhen you find "this-should-not-be" things, like the third parameter in beta 5. I hope this "bug" will be fixed soon.
（更新）这种不匹配应该被视为一个错误。一般来说，当你发现“这不应该”的东西时，你最好发送一个错误报告，比如 beta 5 中的第三个参数。我希望这个“错误”能尽快得到修复。
If you just want to designate your custom UIApplication class, why don't you use Info.plist?
如果您只想指定您的自定义 UIApplication 类，为什么不使用 Info.plist？
NSPrincipalClass | String | $(PRODUCT_MODULE_NAME).MobileUIApplication
(Shown as "Principal class" in non-Raw Keys/Values view.)
（在非原始键/值视图中显示为“主体类”。）
With this in your Info.plist, you can use your MobileUIApplicationwith normal way using @UIApplicationMain.
在您的 Info.plist 中，您可以MobileUIApplication使用@UIApplicationMain.
(ADDITION) Header doc of UIApplicationMain:
（附加）标题文档UIApplicationMain：
// If nil is specified for principalClassName, the value for NSPrincipalClass from the Info.plist is used. If there is no // NSPrincipalClass key specified, the UIApplication class is used. The delegate class will be instantiated using init.
// If nil is specified for principalClassName, the value for NSPrincipalClass from the Info.plist is used. If there is no // NSPrincipalClass key specified, the UIApplication class is used. The delegate class will be instantiated using init.
