[英]What is difference between [NSObject: AnyObject] and AnyObject in swift
In default template we can find the following code: 在默认模板中,我们可以找到以下代码:
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool
Just wonder why here it is [NSObject: AnyObject]? 只是想知道为什么这里是[NSObject:AnyObject]? rather than AnyObject? 而不是AnyObject? What's the different between them? 他们之间有什么不同?
[NSObject: AnyObject]
is a dictionary that allows you to access one object by providing a different object. [NSObject: AnyObject]
是一个字典,允许您通过提供不同的对象来访问一个对象。 Simply putting AnyObject
means that your program doesn't know whether the parameter is a dictionary, a string, and int, or what, and therefore doesn't know how to handle it. 简单地放置AnyObject
意味着你的程序不知道参数是字典,字符串,int,还是什么,因此不知道如何处理它。 Besides, the OS calls that method so you know you are getting a [NSObject: AnyObject]
every time, so why not have the parameter type that. 此外,操作系统调用该方法,因此您知道每次都会获得[NSObject: AnyObject]
,所以为什么不使用参数类型。
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