ios 时间与日历

#pragma mark -Private
//获取一个月多少天：
- (NSUInteger)numberOfDaysInMonth:(NSDate *)date{
    NSCalendar *greCalendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    [greCalendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];
    return [greCalendar rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth forDate:date].length;

}
//获取每月的一号：
- (NSDate *)firstDateOfMonth:(NSDate *)date{
    NSCalendar *greCalendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    [greCalendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];
    NSDateComponents *comps = [greCalendar
                               components:NSCalendarUnitYear | NSCalendarUnitMonth |NSCalendarUnitWeekday | NSCalendarUnitDay
                               fromDate:date];
    comps.day = 1;
    return [greCalendar dateFromComponents:comps];
}
//获取本月一号星期几第几天：
- (NSUInteger)startDayOfWeek:(NSDate *)date
{
    NSCalendar *greCalendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    [greCalendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];//Asia/Shanghai
    NSDateComponents *comps = [greCalendar
                               components:NSCalendarUnitYear | NSCalendarUnitMonth |NSCalendarUnitWeekday | NSCalendarUnitDay
                               fromDate:[self firstDateOfMonth:date]];
    return comps.weekday;
}

//获取上一天的时间：
- (NSDate *)getLastMonth:(NSDate *)date{
    NSCalendar *greCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    [greCalendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];
    NSDateComponents *comps = [greCalendar
                               components:NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay
                               fromDate:date];
    comps.month -= 1;
    return [greCalendar dateFromComponents:comps];
}

//获取下一天的时间：
- (NSDate *)getNextMonth:(NSDate *)date{
    NSCalendar *greCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    [greCalendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];
    NSDateComponents *comps = [greCalendar
                               components:NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay
                               fromDate:date];
    comps.month += 1;
    return [greCalendar dateFromComponents:comps];
}

//获取某一天的data：
- (NSDate *)dateOfDay:(NSInteger)day{
    NSCalendar *greCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    [greCalendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];
    NSDateComponents *comps = [greCalendar
                               components:NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay
                               fromDate:self.tempDate];
    comps.day = day;
    return [greCalendar dateFromComponents:comps];
}

NSDate *tempDate;//当前deta

- (IBAction)上一个:(id)sender {
    
    self.tempDate = [self getLastMonth:self.tempDate];
    self.dateLabel.text = self.tempDate.yyyyMMByLineWithDate;
    [self getDataDayModel:self.tempDate];
}

- (IBAction)下一个:(id)sender {
    self.tempDate = [self getNextMonth:self.tempDate];
    self.dateLabel.text = self.tempDate.yyyyMMByLineWithDate;
    [self getDataDayModel:self.tempDate];
}