iOS 判断两天是否是同一天

/**
 *  是否为同一天
 */
- (BOOL)isSameDay:(NSDate*)date1 date2:(NSDate*)date2
{
    NSCalendar* calendar = [NSCalendar currentCalendar];

    unsigned unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth |  NSCalendarUnitDay;
    NSDateComponents* comp1 = [calendar components:unitFlags fromDate:date1];
    NSDateComponents* comp2 = [calendar components:unitFlags fromDate:date2];

    return [comp1 day]   == [comp2 day] &&
    [comp1 month] == [comp2 month] &&
    [comp1 year]  == [comp2 year];

}