Objective-c中Foundation中的几个常用类

NSString *str7 = @"a"; NSString *str8 = @"b"; NSString * str9 = @"A"; NSLog(@"比较结果为：%@",[str7 compare:str8]?@"YES":@"NO");//比较结果为：YES //忽略大小写 NSLog(@"忽略大小写1，%ld",[str7 caseInsensitiveCompare:str8]);//忽略大小写1，-1 NSLog(@"忽略大小写2，%ld",[str9 caseInsensitiveCompare:str7]);//忽略大小写2，0