iOS 获取当前日期是周几

获取当前日期月份的第一天/最后一天日期
获取当前日期是周几

//获取日期date对应月的第一天日期
+ (NSString *)getMonthFirstDayWithDate:(NSDate *)date format:(NSString *)aformat;
//获取日期date对应月的最后一天日期
+ (NSString *)getMonthLastDayWithDate:(NSDate *)date format:(NSString *)aformat;
//获取对应日期是周几
+ (NSInteger)getWeekDayFromDate:(NSDate *)date;


+ (NSString *)getMonthFirstDayWithDate:(NSDate *)date format:(NSString *)aformat{
    NSDate *newDate = date;
    double interval = 0;
    NSDate *firstDate = nil;
    NSCalendar *calendar = [NSCalendar currentCalendar];
    BOOL bl = [calendar rangeOfUnit:NSCalendarUnitMonth startDate:& firstDate interval:&interval forDate:newDate];
    if (bl) {
        NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
        [myDateFormatter setDateFormat:aformat];
        NSString *firstString = [myDateFormatter stringFromDate: firstDate];
        return firstString;
    }
    return @"";
}
+ (NSString *)getMonthLastDayWithDate:(NSDate *)date format:(NSString *)aformat{
    NSDate *newDate = date;
    double interval = 0;
    NSDate *firstDate = nil;
    NSDate *lastDate = nil;
    NSCalendar *calendar = [NSCalendar currentCalendar];
    BOOL bl = [calendar rangeOfUnit:NSCalendarUnitMonth startDate:& firstDate interval:&interval forDate:newDate];
    if (bl) {
        lastDate = [firstDate dateByAddingTimeInterval:interval - 1];
        NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
        [myDateFormatter setDateFormat:aformat];
        NSString *lastString = [myDateFormatter stringFromDate: lastDate];
        return lastString;
    }
    return @"";
}

+ (NSInteger)getWeekDayFromDate:(NSDate *)date{
    NSArray *tempWeek = @[@"7",@"1",@"2",@"3",@"4",@"5",@"6"];
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    
    NSDateComponents *comps = [[NSDateComponents alloc] init];
    
    NSInteger unitFlags = NSCalendarUnitYear |NSCalendarUnitMonth | NSCalendarUnitDay |NSCalendarUnitWeekday | NSCalendarUnitHour |NSCalendarUnitMinute |NSCalendarUnitSecond;
    
    comps = [calendar components:unitFlags fromDate:date];
    //  1、2、3、4、5、6、7 分别对应 周日、周一、周二、周三、周四、周五、周六
    NSInteger week = [comps weekday];
    NSLog(@"---%ld",week);
  //  调整后 1 代表 周一
    return  [tempWeek[week-1] integerValue] ;
    
}