Hi I have an array having 100 element. and each element is of type class Data with the following members:
name
price
stock
description
How can I sort the array on based on the price member of class Data?
NSSortDescriptor *priceDescriptor = [[[NSSortDescriptor alloc] initWithKey:#"price" ascending:YES] autorelease]; // ascending YES or NO depends on your requirement
NSArray *sortDescriptors = [NSArray arrayWithObject: priceDescriptor];
NSArray *sortedArray = [yourArray sortedArrayUsingDescriptors:sortDescriptors];
also see this
if you have method for price the object within array class you can use NSComparisonResult:
- (NSComparisonResult) compareprice : (id) element
{
return [price compare: [element price ]];
}
Related
I am stuck here......
I have two arrays Arr_title and Arr_distance
I get sorted Arr_distance using this method
NSSortDescriptor *sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:#"self" ascending:YES]autorelease];
sortedFloats = [appDel.Arr_distance sortedArrayUsingDescriptors:
[NSArray arrayWithObject:sortDescriptor]];
but problem is that i want to sort Arr_title according to index of sortedFloats array...
thx in advance for help me..........
Try this,
NSDictionary *dict = [NSDictionary dictionaryWithObjects:Arr_title forKeys:Arr_distance];
NSSortDescriptor *sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:#"self" ascending:YES] autorelease];
sortedFloats = [appDel.Arr_distance sortedArrayUsingDescriptors:
[NSArray arrayWithObject:sortDescriptor]];
NSMutableArray *sortedTitles = [NSMutableArray array];
for (NSString *key in sortedFloats) {//or just use sortedTitles = [dict objectsForKeys:sortedFloats notFoundMarker:[NSNull null]];
[sortedTitles addObject:[dict valueForKey:key]];
}
NSLog(#"%#",sortedValues);
sortedTitles should give you the array sorted in the same order as sortedFloats.
hey instead of taking two different array take 1 dictionary with key title,distance save that dictionary in array then sort that array So you have got combination together so there is no any problem due to mapping in any sort(by title & by distance).
if i understand your question right , you can use NSDictionary for the same task
NSMutableArray *array = [NSMutableArray arrayWithArray:#[ #{#"title" : #"City1",#"dist" : #5},
# {#"title" : #"City2",#"dist" : #2.3 },
#{#"title" : #"City3",#"dist" : #11.0 },
#{#"title" : #"City4",#"dist" : #1.0},
#{#"title" : #"City5",#"dist" : #.5},
#{#"title" : #"City6",#"dist" : #13 }]];
NSLog(#"dict<%#>",array);
NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:#"dist" ascending:YES];
NSArray *sortarray = [array sortedArrayUsingDescriptors:[NSArray arrayWithObject:sort]];
NSLog(#"sort array = <%#>",sortarray);
I got the solution see following code.........
NSSortDescriptor *sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:#"self" ascending:YES]autorelease];
sortedFloats = [appDel.Arr_distance sortedArrayUsingDescriptors:
[NSArray arrayWithObject:sortDescriptor]];
NSLog(#" Sorted Array : %#", sortedFloats);
NSDictionary *dictTitle = [NSDictionary dictionaryWithObjects:Arr_title forKeys:appDel.Arr_distance];
// Sort the second array based on the sorted first array
sortedTitle = [dictTitle objectsForKeys:sortedFloats notFoundMarker:[NSNull null]];
NSLog(#" Sorted Title : %#",sortedTitle);
// Put the two arrays into a dictionary as keys and values
NSDictionary *dictAddress = [NSDictionary dictionaryWithObjects:Arr_address forKeys:appDel.Arr_distance];
// Sort the second array based on the sorted first array
sortedAddress = [dictAddress objectsForKeys:sortedFloats notFoundMarker:[NSNull null]];
NSLog(#" Sorted Address : %#",sortedAddress);
Dont forgot to retain your arrays if use in another method ....
So I have the kind of classic situation where I want to group my tableView by Month/Year. I have a member of my conference object called beginDateSearchString that I use to put different conference into buckets; my problem is in the next part where I try and fail to use a NSSortDescriptor to sort each bucket by beginDate (which is a date).
I am getting an error related to unsorted not being able to receive sort descriptor type selectors.
Here is the disgusting code:
- (NSArray *)arrayOfDateSortedEvents {
NSMutableArray *sortedArray = [[NSMutableArray alloc] init];
NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
//place into buckets
for (WSConference *conference in self.arrayOfEvents) {
if (![dictionary objectForKey:[conference beginDateSearchString]]) {
NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:conference,nil];
[dictionary setObject:array forKey:[conference beginDateSearchString]];
}
else {
[[dictionary objectForKey:[conference beginDateSearchString]] addObject:conference];
}
}
//sort each bucket by descriptor beginDate
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:#"beginDate" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:descriptor];
for (NSMutableArray *unsorted in dictionary) {
[unsorted sortUsingDescriptors:sortDescriptors];
}
// now, unkey and add dictionary in order
while ([dictionary count] > 0) {
NSString *lowest = nil;
for (NSMutableArray *array in dictionary) {
if (!lowest)
lowest = [[dictionary allKeysForObject:array] objectAtIndex:0];
else {
if ([(WSConference *)[array objectAtIndex:0] beginDate] < [[dictionary objectForKey:lowest] beginDate])
lowest = [[dictionary allKeysForObject:array] objectAtIndex:0];
}
}
[sortedArray addObject:[dictionary objectForKey:lowest]];
[dictionary removeObjectForKey:lowest];
}
return sortedArray;
}
You want to probably filter the array in addition to sorting. See NSPredicate and the NSArray method -filteredArrayUsingPredicate: Then create an eventsByDateArray of the eventArrays created by the filter. Then in your table view delegate for creating the cells, if everything is ordered properly, the first section would represent the date of the events in the eventArray that is the first object of the eventsByDateArray and the table rows would consist of the events in the eventArray. And so on for each date.
Added
Your fast enumeration is incorrect. You enumerate through the keys of the dictionary. So in your code unsorted equals each of the keys as it enumerates. This is a GREAT lesson to everyone. It does not matter how you 'type' a variable. When Objective-C compiles it turns them all into id. So NSMutableArray *unsorted is not an NSMutableArray unless it is assigned to an NSMutableArray. If you assign unsorted to an NSString it will be an NSString. The fast enumerator for a dictionary works using the keys. So, in this case, unsorted becomes an NSString.
Instead of:
for (NSMutableArray *unsorted in dictionary) {
[unsorted sortUsingDescriptors:sortDescriptors];
}
you should have this:
for (id key in dictionary) {
NSMutableArray *unsorted = [dictionary objectForKey:key];
[unsorted sortUsingDescriptors:sortDescriptors];
}
I have an array of dictionaries. Within each dictionary, there is a a key dateOfInfo (an NSDate) and several other things. I want to sort the array by each dictionaries dateOfInfo with the most recent being the first result.
How can I do this?
You can sort using NSSortDescription, e.g.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey: #"dateOfInfo" ascending: NO];
NSArray *sortedArray = [array sortedArrayUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
You can also use the method
- (NSArray *)sortedArrayUsingFunction:(NSInteger (*)(id, id, void *))comparator context:(void *)context
The basic bubble sorting algorithm would work. In this case you need to loop through your array, use valueForKey message on [array objectAtIndex:] to get the NSDate values. For comparing dates see this post . So if you are sorting in ascending order of date, just add the object with the lower date (remember bubble sort comparisons?) to an array which will hold your sorted result.
try like this,
NSDateFormatter *fmtDate = [[NSDateFormatter alloc] init];
[fmtDate setDateFormat:#"yyyy-MM-dd'T'HH:mm:ss"];
NSComparator compareDates = ^(id string1, id string2)
{
NSDate *date1 = [fmtDate dateFromString:string1];
NSDate *date2 = [fmtDate dateFromString:string2];
return [date1 compare:date2];
};
NSSortDescriptor * sortDesc1 = [[NSSortDescriptor alloc] initWithKey:#"StartTime" ascending:YES comparator:compareDates];
[youArray sortUsingDescriptors:#[sortDesc1]];
I have a NSMutableArray containing NSStrings of various lengths. How would I go about sorting the array by the string length?
See my answer to sorting arrays with custom objects:
NSSortDescriptor *sortDesc= [[NSSortDescriptor alloc] initWithKey:#"length" ascending:YES];
[myArray sortUsingDescriptors:#[sortDesc]];
This is how I did it (love me some blocks!)
_objects = [matchingWords sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
NSNumber *alength = [NSNumber numberWithInt:((NSString*)a).length];
NSNumber *blength = [NSNumber numberWithInt:((NSString*)b).length];
return [alength compare:blength];
}];
I have two arrays used in a small game.
If the player gets a score above a certain value their name & score gets output via
an UILabel.
NSArray *namesArray = [mainArray objectForKey:#"names"];
NSArray *highScoresArray = [mainArray objectForKey:#"scores"];
I need the UILabels to display with the highest score in descending order, with the corresponding name. I've used an NSSortDescriptor to sort the score values numerically.
NSSortDescriptor *sortDescriptor;
sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:#"self"
ascending:NO] autorelease];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
NSArray *sortedScore = [[NSArray alloc]init];
sortedScore = [scoresArray sortedArrayUsingDescriptors:sortDescriptors];
NSMutableArray *scoreLabels = [NSMutableArray arrayWithCapacity:10];
[scoreLabels addObject:scoreLabel1];
......
NSUInteger _index = 0;
for (NSNumber *_number in sortedScore) {
UILabel *_label = [scoreLabels objectAtIndex:_index];
_label.text = [NSString stringWithFormat:#"%d", [_number intValue]];
_index++;
}
This works well enough as the scores now display in descending order.
The problem is that I need the corresponding name to also display according in the new sorted order.
I cant use the same sort selector and I don't wont to sort them alphabetically, they need
to correspond to the name/score values that were first input.
Thanks in advance
You need to put the name and the score together into a single instance of NSDictionary, and then have an NSArray of those NSDictionary instances. Then when you sort by score, you can pull up the corresponding name.