相信大家对Object-C中nil和Nil的用法是一头雾水,我也是。最近看了Mattt Thompson 大神的blog,终于弄明白了。直接上图,我相信大家看了图,一眼就记住了。
Symbol | Value | Meaning |
---|---|---|
NULL | (void *)0 | literal null value for C pointers |
nil | (id)0 | literal null value for Objective-C objects |
Nil | (Class)0 | literal null value for Objective-C classes |
NSNull | [NSNull null] | singleton object used to represent null |