1.the basis on which something is grounded;
there is little foundation for his objections
2.an institution supported by an endowment
3.the fundamental assumptions from which something is begun or developed or calculated or explained;
the whole argument rested on a basis of conjecture
4.lowest support of a structure;
it was built on a base of solid rock
5.education or instruction in the fundamentals of a field of knowledge;
he lacks the foundation necessary for advanced study
6.a woman's undergarment worn to give shape to the contours of the body
7.the act of starting something for the first time; introducing something new;
she looked forward to her initiation as an adult
Foundation類層次 Foundation類層次的根是NSObject類,它(和NSObject及NSCopying協(xié)議一起)定義了基本的對象屬性和行為。 Foundation框架的剩余部分由幾組相互關(guān)聯(lián)的類和一些獨(dú)立的類組成。有一些代表基本數(shù)據(jù)類型的類,如字符串、字節(jié)數(shù)組、用于存儲其它對象的集合類;一些代表系統(tǒng)信息的類,如日期類;還有一些代表系統(tǒng)實體的類,比如端口、線程、和進(jìn)程。圖1、圖2、和圖3所示的類層次描述了這些類的邏輯分組及其繼承關(guān)系。 Fo