什么是 NSSearchPathForDirectoriesInDomains？
[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]
我以前知道向对象发送消息是一种调用方法。但是，我无法识别 NSSearchPathForDirectoriesInDomains 是什么。是C风格的函数吗？如果是，那么为什么在所有 message 风格的调用中我们有这样的函数？
[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]
I used to know that sending a message to the object is kind of calling the method. However, I can't recognize what is NSSearchPathForDirectoriesInDomains. Is it C style function? If yes then why among all message style calls we have thing kind of function?
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是的，它是一个普通的 C 函数，获取并返回 Objective-C 对象。
至于为什么......苹果可能没有找到一个很好的类来放入它。:-) 不过说真的，它可能是
UIApplication或NSApplication上的静态方法> 或类似的，但很难证明其合理性，并且非常特定于系统（在 OS X 上你可以将它放在NSApplication中，在 iOS 上你可以将它放在UIApplication中）。Yes, it's a plain C function taking and returning objective-c objects.
As to the why... Apple probably didn't find a nice class to put it in. :-) Seriously though, it could be a static method on
UIApplicationorNSApplicationor similar, but it's hard to justify and quite system-specific (you'd have it inNSApplicationon OS X andUIApplicationon iOS).查看
http://www.techotopia.com/index.php/Working_with_Directories_on_iPhone_OS 和 http://iphonedevelopmentblog.blogspot.com/2011/03/documents- Directory-file-path-iphone.html
我正在研究相同的材料，这些链接提供了有关该主题的详尽信息。
Check out
http://www.techotopia.com/index.php/Working_with_Directories_on_iPhone_OS and http://iphonedevelopmentblog.blogspot.com/2011/03/documents-directory-file-path-iphone.html
I was studying the same material, and these links provide exhaustive information on the subject.