| Name | Typedef | Header | True Value | False Value |
|---|---|---|---|---|
| BOOL | signed char | objc.h | YES | NO |
| bool | _Bool (int) | stdbool.h | true | false |
| Boolean | unsigned char | MacTypes.h | TRUE | FALSE |
| NSNumber | __NSCFBoolean | Foundation.h | @(YES) | @(NO) |
| CFBooleanRef | struct | CoreFoundation.h | kCFBooleanTrue |
iOS开发——语法OC篇&BOOL / bool / Boolean / NSCFBoolean四者区别
原文：http://www.cnblogs.com/stronger-ios-lcx/p/5627756.html