Foundation.framework是属于CoreService层还是CocoaTouch层？
Foundation.framework is belong to CoreService layer or CocoaTouch Layer?
Cocoa（触摸）文档here说：
Cocoa Touch, which includes Foundation and UIKit frameworks, is used for developing applications that run on iOS.
但是核心服务层文档here说：
The Core Services layer contains fundamental system services for apps. Key among these services are the Core Foundation and Foundation frameworks, which define the basic types that all apps use. This layer also contains individual technologies to support features such as location, iCloud, social media, and networking."
那么Foundation.framework属于哪一层
Cocoa（触摸）是层堆栈的包罗万象的保护伞。 Cocoa（触摸）应用层是该堆栈中的特定层，有时简称为应用层。
Core Foundation框架和Foundation框架都是Core Services层的一部分。
正如您提到的，here is the Apple Documentation 关于这个主题。
Cocoa（触摸）文档here说：
Cocoa Touch, which includes Foundation and UIKit frameworks, is used for developing applications that run on iOS.
但是核心服务层文档here说：
The Core Services layer contains fundamental system services for apps. Key among these services are the Core Foundation and Foundation frameworks, which define the basic types that all apps use. This layer also contains individual technologies to support features such as location, iCloud, social media, and networking."
那么Foundation.framework属于哪一层
Cocoa（触摸）是层堆栈的包罗万象的保护伞。 Cocoa（触摸）应用层是该堆栈中的特定层，有时简称为应用层。
Core Foundation框架和Foundation框架都是Core Services层的一部分。
正如您提到的，here is the Apple Documentation 关于这个主题。