转：http://www.cnblogs.com/kingbo/p/3966855.html

1. 获取当前月份有多少天NSCalendar *calendar = [NSCalendarcurrentCalendar]; NSRange range = [calendarrangeOfUnit:NSDayCalendarUnitinUnit:NSMonthCalendarUnitforDate:[NSDatedate]]; NSUInteger numberOfDaysInMonth = range.length;  numberOfDaysInMonth 即为当月的天数。更多用法查看NSCalendar， NSDateComponents帮助文档   2. 获取当前年份和月份和天数 NSCalendar *calendar = [NSCalendar currentCalendar]; unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit; NSDateComponents *components = [calendar components:unitFlags fromDate:[NSDate date]]; NSInteger iCurYear = [components year];  //当前的年份 NSInteger iCurMonth = [components month];  //当前的月份 NSInteger iCurDay = [components day];  // 当前的号数