什么是swift代码执行的入口点? [英] What is the entry point of swift code execution?
问题描述
在swift中没有 main()
方法。程序必须从某处开始执行。那么什么是swift代码执行的入口点,它是如何决定的?
There is no main()
method in swift. The program must start the execution from somewhere. So what is the entry point of swift code execution and how is it decided?
推荐答案
模块中的文件名为 main.swift
。 main.swift
是唯一允许在顶层具有表达式和语句的文件(模块中的所有其他Swift文件只能包含声明)。
The entry point in a plain Swift module is the file in the module called main.swift
. main.swift
is the only file which is allowed to have expressions and statements at the top level (all other Swift files in the module can only contain declarations).
Cocoa Touch使用 @UIApplicationMain
属性。 com / library / ios / documentation / UIKit / Reference / UIApplicationDelegate_Protocol / index.html> UIApplicationDelegate
而不是 main.swift
文件来标记入口点。 Cocoa曾经使用最少的 main.swift
文件,只是简单地调用 NSApplicationMain
,但的Xcode 6.1 使用 <$ @NSApplicationMain 属性 .html> NSApplicationDelegate
。
Cocoa Touch uses the @UIApplicationMain
attribute on an implementation of UIApplicationDelegate
instead of a main.swift
file to mark the entry point. Cocoa used to use a minimal main.swift
file which simply called NSApplicationMain
, but as of Xcode 6.1 uses the @NSApplicationMain
attribute on an implementation of NSApplicationDelegate
.
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