UITableView scroll to section that is closest to todays date - ios

Question

I have a tableview with a calendar it's appointments in it. Each day is a separate section.
You can see what I mean over here
Now I want that the tableview scrolls to the section of today or if there is no section for today to the closest one.
I know that I should use the following piece of code:
[tableView scrollToRowAtIndexPath:scrollIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
Now I have an NSMutableDictionary that contains my sorted Appointments/day. You can see the function below:
-(NSDictionary *)sortKalendar:(NSMutableArray *)appointments{
NSMutableDictionary *buffer = [[NSMutableDictionary alloc] init];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"dd-MM-yyyy"];
for (int i = 0; i < appointments.count; i++) {
Appointment *object = [appointments objectAtIndex:i];
NSString *date = [formatter stringFromDate:object.app_start];
if(!(date == NULL) ){
NSLog(#"date is %#",date);
if ([buffer objectForKey:date]) {
[(NSMutableArray *)[buffer objectForKey:date] addObject:object];
} else {
NSMutableArray *mutableArray = [[NSMutableArray alloc] initWithObjects:object, nil];
[buffer setObject:mutableArray forKey:date];
}
}
}
NSDictionary *result = [NSDictionary dictionaryWithDictionary:buffer];
return result;
}
My question is now, how can I find the correct NSIndexpath ?
Thanks in advance !
EDIT
At the moment I'm using the following. But something is still not right.
NSArray *keys = [dictAppointments allKeys];
NSLog(#"KEYS ARE %#",keys) ;
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"dd-MM-yyyy"];
NSArray *sortedArray = [keys sortedArrayUsingComparator:^(id obj1, id obj2) {
NSDate *date1 = [formatter dateFromString:obj1];
NSDate *date2 = [formatter dateFromString:obj2];
NSNumber *interval1 = [NSNumber numberWithDouble:[date1 timeIntervalSinceNow]];
NSNumber *interval2 = [NSNumber numberWithDouble:[date2 timeIntervalSinceNow]];
return (NSComparisonResult)[interval1 compare:interval2];
}];
NSLog(#"Sorted Array %#",sortedArray);
NSString *closestDateString = [sortedArray objectAtIndex:0];
NSLog(#"Closest date string is %#",closestDateString);
int section = [keys indexOfObject:closestDateString];
NSIndexPath *scrollIndexPath = [NSIndexPath indexPathForRow:0 inSection:section];
[tableView scrollToRowAtIndexPath:scrollIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
This gives me the following logs:
2014-01-07 13:28:42.420 Adsolut[9579:60b] KEYS ARE (
"03-12-2013",
"20-12-2013",
"17-12-2013",
"05-01-2014",
"21-12-2013",
"31-12-2013",
"04-01-2014",
"06-01-2014",
"16-01-2014",
"29-12-2013",
"03-01-2014",
"11-01-2014",
"18-12-2013",
"31-01-2014"
)
2014-01-07 13:28:42.437 Adsolut[9579:60b] Sorted Array (
"03-12-2013",
"17-12-2013",
"18-12-2013",
"20-12-2013",
"21-12-2013",
"29-12-2013",
"31-12-2013",
"03-01-2014",
"04-01-2014",
"05-01-2014",
"06-01-2014",
"11-01-2014",
"16-01-2014",
"31-01-2014"
)

Answer 1

You can sort the array using time interval between appointment date and current date,
NSArray *keys = [yourDictionary allKeys];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"dd-MM-yyyy"];
NSArray *sortedArray = [keys sortedArrayUsingComparator:^(id obj1, id obj2) {
NSDate *date1 = [formatter dateFromString:obj1];
NSDate *date2 = [formatter dateFromString:obj2];
NSNumber *interval1 = [NSNumber numberWithDouble:abs([date1 timeIntervalSinceNow])];
NSNumber *interval2 = [NSNumber numberWithDouble:abs([date2 timeIntervalSinceNow])];
return (NSComparisonResult)[interval1 compare:interval2];
}];
And the closest date by,
NSString *closestDateString = [sortedArray objectAtIndex:0];
And from that,
int section = [keys indexOfObject:closestDateString];
NSIndexPath *scrollIndexPath = [NSIndexPath indexPathForRow:0 inSection:section];

Answer 2

Get the list of dates (from your dictionary or one you already have). Sort it. Loop over it (indexOfObjectPassingTest:) to find the date >= today (or use a predicate to filter and then take the first item from the result and get the index).

Answer 3

You have a sorted date array, don't you? Let's say it as dateArray.
Get today date object: NSDate * today = [NSDate date];
Search for dateArray to the nearest date, get the index of nearest date.
NSDate * today = [NSDate date] ;
__block NSUInteger section = NSNotFound ;
__block NSTimeInterval timeInterval = NSTimeIntervalSince1970 ;
[dateArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSDate * date = obj ;
NSTimeInterval ti = [today timeIntervalSinceDate:date] ;
if (ti < 0)
ti = -ti ;
if (ti <= timeInterval) {
section = idx ;
timeInterval = ti ;
} else {
*stop = YES ;
}
}] ;
You know the section index now, let's say it as sectionIndex, the first row index in the section is 0.
So the NSIndexPath is [NSIndexPath indexPathForRow:0 inSection:sectionIndex]