iOS自定义日期demo分享

 //3.获取这个月总天数,填充数据源
 NSRange range = [calendar rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth forDate:self.currentDate];
 NSUInteger numberOfDaysInMonth = range.length;
 NSLog(@"%lu", (unsigned long)numberOfDaysInMonth);
 
 //4.获取这个月的第一天为周几
 NSCalendar *cal = [NSCalendar currentCalendar];
 NSDateComponents *comps = [cal
    components:NSCalendarUnitYear | NSCalendarUnitMonth
    fromDate:self.currentDate];
 lastMonthComps.day = 1;
 NSDate *firstDay = [cal dateFromComponents:comps];
 NSCalendarUnit calendarUnit = NSCalendarUnitWeekday;
 NSDateComponents *firsComponents = [cal components:calendarUnit fromDate:firstDay];
 
 NSLog(@"%@", [_weekdays objectAtIndex:firsComponents.weekday]);