How to sort an NSMutableArray with custom objects in it?

What I want to do seems pretty simple, but I can’t find any answers on the web. I have an NSMutableArray of objects, let’s say they are ‘Person’ objects. I want to sort the NSMutableArray by Person.birthDate which is an NSDate.

I think it has something to do with this method:

  • Current view controller from AppDelegate?
  • Getting data out of a closure in swift
  • Workaround for 'background-attachment: fixed' which is not working in iOS4
  • Share my iPhone app for testing
  • Unknown crash reason (with CrashReport attached) SIGTRAP. AFNetworking?
  • NSString containsString crashes
  • NSArray *sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(???)];
    

    In Java I would make my object implement Comparable, or use Collections.sort with an inline custom comparator…how on earth do you do this in Objective-C?

    22 Solutions Collect From Internet About “How to sort an NSMutableArray with custom objects in it?”

    Compare method

    Either you implement a compare-method for your object:

    - (NSComparisonResult)compare:(Person *)otherObject {
        return [self.birthDate compare:otherObject.birthDate];
    }
    
    NSArray *sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(compare:)];
    

    NSSortDescriptor (better)

    or usually even better:

    NSSortDescriptor *sortDescriptor;
    sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"birthDate"
                                               ascending:YES];
    NSArray *sortedArray = [drinkDetails sortedArrayUsingDescriptors:@[sortDescriptor]];
    

    You can easily sort by multiple keys by adding more than one to the array. Using custom comparator-methods is possible as well. Have a look at the documentation.

    Blocks (shiny!)

    There’s also the possibility of sorting with a block since Mac OS X 10.6 and iOS 4:

    NSArray *sortedArray;
    sortedArray = [drinkDetails sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
        NSDate *first = [(Person*)a birthDate];
        NSDate *second = [(Person*)b birthDate];
        return [first compare:second];
    }];
    

    Performance

    The -compare: and block-based methods will be quite a bit faster, in general, than using NSSortDescriptor as the latter relies on KVC. The primary advantage of the NSSortDescriptor method is that it provides a way to define your sort order using data, rather than code, which makes it easy to e.g. set things up so users can sort an NSTableView by clicking on the header row.

    See the NSMutableArray method sortUsingFunction:context:

    You will need to set up a compare function which takes two objects (of type Person, since you are comparing two Person objects) and a context parameter.

    The two objects are just instances of Person. The third object is a string, e.g. @”birthDate”.

    This function returns an NSComparisonResult: It returns NSOrderedAscending if PersonA.birthDate < PersonB.birthDate. It will return NSOrderedDescending if PersonA.birthDate > PersonB.birthDate. Finally, it will return NSOrderedSame if PersonA.birthDate == PersonB.birthDate.

    This is rough pseudocode; you will need to flesh out what it means for one date to be “less”, “more” or “equal” to another date (such as comparing seconds-since-epoch etc.):

    NSComparisonResult compare(Person *firstPerson, Person *secondPerson, void *context) {
      if ([firstPerson birthDate] < [secondPerson birthDate])
        return NSOrderedAscending;
      else if ([firstPerson birthDate] > [secondPerson birthDate])
        return NSOrderedDescending;
      else 
        return NSOrderedSame;
    }
    

    If you want something more compact, you can use ternary operators:

    NSComparisonResult compare(Person *firstPerson, Person *secondPerson, void *context) {
      return ([firstPerson birthDate] < [secondPerson birthDate]) ? NSOrderedAscending : ([firstPerson birthDate] > [secondPerson birthDate]) ? NSOrderedDescending : NSOrderedSame;
    }
    

    Inlining could perhaps speed this up a little, if you do this a lot.

    I did this in iOS 4 using a block.
    Had to cast the elements of my array from id to my class type.
    In this case it was a class called Score with a property called points.

    Also you need to decide what to do if the elements of your array are not the right type, for this example I just returned NSOrderedSame, however in my code I though an exception.

    NSArray *sorted = [_scores sortedArrayUsingComparator:^(id obj1, id obj2){
        if ([obj1 isKindOfClass:[Score class]] && [obj2 isKindOfClass:[Score class]]) {
            Score *s1 = obj1;
            Score *s2 = obj2;
    
            if (s1.points > s2.points) {
                return (NSComparisonResult)NSOrderedAscending;
            } else if (s1.points < s2.points) {
                return (NSComparisonResult)NSOrderedDescending;
            }
        }
    
        // TODO: default is the same?
        return (NSComparisonResult)NSOrderedSame;
    }];
    
    return sorted;
    

    PS: This is sorting in descending order.

    Starting in iOS 4 you can also use blocks for sorting.

    For this particular example I’m assuming that the objects in your array have a ‘position’ method, which returns an NSInteger.

    NSArray *arrayToSort = where ever you get the array from... ;
    NSComparisonResult (^sortBlock)(id, id) = ^(id obj1, id obj2) 
    {
        if ([obj1 position] > [obj2 position]) 
        { 
            return (NSComparisonResult)NSOrderedDescending;
        }
        if ([obj1 position] < [obj2 position]) 
        {
            return (NSComparisonResult)NSOrderedAscending;
        }
        return (NSComparisonResult)NSOrderedSame;
    };
    NSArray *sorted = [arrayToSort sortedArrayUsingComparator:sortBlock];
    

    Note: the “sorted” array will be autoreleased.

    I tried all, but this worked for me. In a class I have another class named “crimeScene“, and want to sort by a property of “crimeScene“.

    This works like a charm:

    NSSortDescriptor *sorter = [[NSSortDescriptor alloc] initWithKey:@"crimeScene.distance" ascending:YES];
    [self.arrAnnotations sortUsingDescriptors:[NSArray arrayWithObject:sorter]];
    

    Your Person objects need to implement a method, say compare: which takes another Person object, and return NSComparisonResult according to the relationship between the 2 objects.

    Then you would call sortedArrayUsingSelector: with @selector(compare:) and it should be done.

    There are other ways, but as far as I know there is no Cocoa-equiv of the Comparable interface. Using sortedArrayUsingSelector: is probably the most painless way to do it.

    There is a missing step in Georg Schölly’s second answer, but it works fine then.

    NSSortDescriptor *sortDescriptor;
    sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:@"birthDate"
                                                  ascending:YES] autorelease];
    NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
    NSArray *sortedArray;
    sortedArray = [drinkDetails sortedArrayUsingDescriptor:sortDescriptors];
    
    NSSortDescriptor *sortDescriptor;
    sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:@"birthDate" ascending:YES] autorelease];
    NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
    NSArray *sortedArray;
    sortedArray = [drinkDetails sortedArrayUsingDescriptors:sortDescriptors];
    

    Thanks, it’s working fine…

    iOS 4 blocks will save you 🙂

    featuresArray = [[unsortedFeaturesArray sortedArrayUsingComparator: ^(id a, id b)  
    {
        DMSeatFeature *first = ( DMSeatFeature* ) a;
        DMSeatFeature *second = ( DMSeatFeature* ) b;
    
        if ( first.quality == second.quality )
            return NSOrderedSame;
        else
        {
            if ( eSeatQualityGreen  == m_seatQuality || eSeatQualityYellowGreen == m_seatQuality || eSeatQualityDefault  == m_seatQuality )
            {
                if ( first.quality < second.quality )
                    return NSOrderedAscending;
                else
                    return NSOrderedDescending;
            }
            else // eSeatQualityRed || eSeatQualityYellow
            {
                if ( first.quality > second.quality )
                    return NSOrderedAscending;
                else
                    return NSOrderedDescending;
            } 
        }
    }] retain];
    

    http://sokol8.blogspot.com/2011/04/sorting-nsarray-with-blocks.html a bit of description

    For NSMutableArray, use the sortUsingSelector method. It sorts it-place, without creating a new instance.

    If you’re just sorting an array of NSNumbers, you can sort them with 1 call:

    [arrayToSort sortUsingSelector: @selector(compare:)];
    

    That works because the objects in the array (NSNumber objects) implement the compare method. You could do the same thing for NSString objects, or even for an array of custom data objects that implement a compare method.

    Here’s some example code using comparator blocks. It sorts an array of dictionaries where each dictionary includes a number in a key “sort_key”.

    #define SORT_KEY @\"sort_key\"
    
    [anArray sortUsingComparator: 
     ^(id obj1, id obj2) 
      {
      NSInteger value1 = [[obj1 objectForKey: SORT_KEY] intValue];
      NSInteger value2 = [[obj2 objectForKey: SORT_KEY] intValue];
      if (value1 > value2) 
    {
      return (NSComparisonResult)NSOrderedDescending;
      }
    
      if (value1 < value2) 
    {
      return (NSComparisonResult)NSOrderedAscending;
      }
        return (NSComparisonResult)NSOrderedSame;
     }];
    

    The code above goes through the work of getting an integer value for each sort key and comparing them, as an illustration of how to do it. Since NSNumber objects implement a compare method, it could be rewritten much more simply:

     #define SORT_KEY @\"sort_key\"
    
    [anArray sortUsingComparator: 
    ^(id obj1, id obj2) 
     {
      NSNumber* key1 = [obj1 objectForKey: SORT_KEY];
      NSNumber* key2 = [obj2 objectForKey: SORT_KEY];
      return [key1 compare: key2];
     }];
    

    or the body of the comparator could even be distilled down to 1 line:

      return [[obj1 objectForKey: SORT_KEY] compare: [obj2 objectForKey: SORT_KEY]];
    

    I tend to prefer simple statements and lots of temporary variables because the code is easier to read, and easier to debug. The compiler optimizes away the temporary variables anyway, so there is no advantage to the all-in-one-line version.

    I have created a small library of category methods, called Linq to ObjectiveC, that makes this sort of thing more easy. Using the sort method with a key selector, you can sort by birthDate as follows:

    NSArray* sortedByBirthDate = [input sort:^id(id person) {
        return [person birthDate];
    }]
    

    I just done multi level sorting based on custom requirement.

    //sort the values

        [arrItem sortUsingComparator:^NSComparisonResult (id a, id b){
    
        ItemDetail * itemA = (ItemDetail*)a;
        ItemDetail* itemB =(ItemDetail*)b;
    
        //item price are same
        if (itemA.m_price.m_selling== itemB.m_price.m_selling) {
    
            NSComparisonResult result=  [itemA.m_itemName compare:itemB.m_itemName];
    
            //if item names are same, then monogramminginfo has to come before the non monograme item
            if (result==NSOrderedSame) {
    
                if (itemA.m_monogrammingInfo) {
                    return NSOrderedAscending;
                }else{
                    return NSOrderedDescending;
                }
            }
            return result;
        }
    
        //asscending order
        return itemA.m_price.m_selling > itemB.m_price.m_selling;
    }];
    

    https://sites.google.com/site/greateindiaclub/mobil-apps/ios/multilevelsortinginiosobjectivec

    I’ve used sortUsingFunction:: in some of my projects:

    int SortPlays(id a, id b, void* context)
    {
        Play* p1 = a;
        Play* p2 = b;
        if (p1.score<p2.score) 
            return NSOrderedDescending;
        else if (p1.score>p2.score) 
            return NSOrderedAscending;
        return NSOrderedSame;
    }
    
    ...
    [validPlays sortUsingFunction:SortPlays context:nil];
    
    -(NSMutableArray*) sortArray:(NSMutableArray *)toBeSorted 
    {
      NSArray *sortedArray;
      sortedArray = [toBeSorted sortedArrayUsingComparator:^NSComparisonResult(id a, id b) 
      {
        return [a compare:b];
     }];
     return [sortedArray mutableCopy];
    }
    

    You can use the following generic method for your purpose. It should solve your issue.

    //Called method
    -(NSMutableArray*)sortArrayList:(NSMutableArray*)arrDeviceList filterKeyName:(NSString*)sortKeyName ascending:(BOOL)isAscending{
        NSSortDescriptor *sorter = [[NSSortDescriptor alloc] initWithKey:sortKeyName ascending:isAscending];
        [arrDeviceList sortUsingDescriptors:[NSArray arrayWithObject:sorter]];
        return arrDeviceList;
    }
    
    //Calling method
    [self sortArrayList:arrSomeList filterKeyName:@"anything like date,name etc" ascending:YES];
    

    Sorting NSMutableArray is very simple:

    NSMutableArray *arrayToFilter =
         [[NSMutableArray arrayWithObjects:@"Photoshop",
                                           @"Flex",
                                           @"AIR",
                                           @"Flash",
                                           @"Acrobat", nil] autorelease];
    
    NSMutableArray *productsToRemove = [[NSMutableArray array] autorelease];
    
    for (NSString *products in arrayToFilter) {
        if (fliterText &&
            [products rangeOfString:fliterText
                            options:NSLiteralSearch|NSCaseInsensitiveSearch].length == 0)
    
            [productsToRemove addObject:products];
    }
    [arrayToFilter removeObjectsInArray:productsToRemove];
    
    NSSortDescriptor  *sort = [[NSSortDescriptor alloc] initWithKey:@"_strPrice"
                                                     ascending:sortFlag selector:@selector(localizedStandardCompare:)] ;
    

    Sort using NSComparator

    If we want to sort custom objects we need to provide NSComparator, which is used to compare custom objects. The block returns an NSComparisonResult value to denote the ordering of the two objects. So in order to sort whole array NSComparator is used in following way.

    NSArray *sortedArray = [employeesArray sortedArrayUsingComparator:^NSComparisonResult(Employee *e1, Employee *e2){
        return [e1.firstname compare:e2.firstname];    
    }];
    

    Sorts Using NSSortDescriptor
    Let’s assume, as an example, that we have an array containing instances of a custom class, Employee has attributes firstname, lastname and age. The following example illustrates how to create an NSSortDescriptor that can be used to sort the array contents in ascending order by the age key.

    NSSortDescriptor *ageDescriptor = [[NSSortDescriptor alloc] initWithKey:@"age" ascending:YES];
    NSArray *sortDescriptors = @[ageDescriptor];
    NSArray *sortedArray = [employeesArray sortedArrayUsingDescriptors:sortDescriptors];
    

    Sort using Custom Comparisons
    Names are strings, and when you sort strings to present to the user you should always use a localized comparison. Often you also want to perform a case insensitive comparison. Here comes an example with (localizedStandardCompare:) to order the array by last and first name.

    NSSortDescriptor *lastNameDescriptor = [[NSSortDescriptor alloc]
                  initWithKey:@"lastName" ascending:YES selector:@selector(localizedStandardCompare:)];
    NSSortDescriptor * firstNameDescriptor = [[NSSortDescriptor alloc]
                  initWithKey:@"firstName" ascending:YES selector:@selector(localizedStandardCompare:)];
    NSArray *sortDescriptors = @[lastNameDescriptor, firstNameDescriptor];
    NSArray *sortedArray = [employeesArray sortedArrayUsingDescriptors:sortDescriptors];
    

    For reference and detailed discussion please refer:
    https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/SortDescriptors/Articles/Creating.html
    http://www.ios-blog.co.uk/tutorials/objective-c/how-to-sort-nsarray-with-custom-objects/

    in my case, i use “sortedArrayUsingComparator” to sort an array. Look below code.

    contactArray = [[NSArray arrayWithArray:[contactSet allObjects]] sortedArrayUsingComparator:^NSComparisonResult(ContactListData *obj1, ContactListData *obj2) {
        NSString *obj1Str = [NSString stringWithFormat:@"%@ %@",obj1.contactName,obj1.contactSurname];
        NSString *obj2Str = [NSString stringWithFormat:@"%@ %@",obj2.contactName,obj2.contactSurname];
        return [obj1Str compare:obj2Str];
    }];
    

    Also my object is,

        @interface ContactListData : JsonData
    @property(nonatomic,strong) NSString * contactName;
    @property(nonatomic,strong) NSString * contactSurname;
    @property(nonatomic,strong) NSString * contactPhoneNumber;
    @property(nonatomic) BOOL isSelected;
    @end
    

    Swift’s protocols and functional programming makes that very easy you just have to make your class conform to the Comparable protocol, implement the methods required by the protocol and then use the sorted(by: ) high order function to create a sorted array without need to use mutable arrays by the way.

    class Person: Comparable {
        var birthDate: NSDate?
        let name: String
    
        init(name: String) {
            self.name = name
        }
    
        static func ==(lhs: Person, rhs: Person) -> Bool {
            return lhs.birthDate === rhs.birthDate || lhs.birthDate?.compare(rhs.birthDate as! Date) == .orderedSame
        }
    
        static func <(lhs: Person, rhs: Person) -> Bool {
            return lhs.birthDate?.compare(rhs.birthDate as! Date) == .orderedAscending
        }
    
        static func >(lhs: Person, rhs: Person) -> Bool {
            return lhs.birthDate?.compare(rhs.birthDate as! Date) == .orderedDescending
        }
    
    }
    
    let p1 = Person(name: "Sasha")
    p1.birthDate = NSDate() 
    
    let p2 = Person(name: "James")
    p2.birthDate = NSDate()//he is older by miliseconds
    
    if p1 == p2 {
        print("they are the same") //they are not
    }
    
    let persons = [p1, p2]
    
    //sort the array based on who is older
    let sortedPersons = persons.sorted(by: {$0 > $1})
    
    //print sasha which is p1
    print(persons.first?.name)
    //print James which is the "older"
    print(sortedPersons.first?.name)
    
    NSMutableArray *stockHoldingCompanies = [NSMutableArray arrayWithObjects:fortune1stock,fortune2stock,fortune3stock,fortune4stock,fortune5stock,fortune6stock , nil];
    
    NSSortDescriptor *sortOrder = [NSSortDescriptor sortDescriptorWithKey:@"companyName" ascending:NO];
    
    [stockHoldingCompanies sortUsingDescriptors:[NSArray arrayWithObject:sortOrder]];
    
    NSEnumerator *enumerator = [stockHoldingCompanies objectEnumerator];
    
    ForeignStockHolding *stockHoldingCompany;
    
    NSLog(@"Fortune 6 companies sorted by Company Name");
    
        while (stockHoldingCompany = [enumerator nextObject]) {
            NSLog(@"===============================");
            NSLog(@"CompanyName:%@",stockHoldingCompany.companyName);
            NSLog(@"Purchase Share Price:%.2f",stockHoldingCompany.purchaseSharePrice);
            NSLog(@"Current Share Price: %.2f",stockHoldingCompany.currentSharePrice);
            NSLog(@"Number of Shares: %i",stockHoldingCompany.numberOfShares);
            NSLog(@"Cost in Dollars: %.2f",[stockHoldingCompany costInDollars]);
            NSLog(@"Value in Dollars : %.2f",[stockHoldingCompany valueInDollars]);
        }
        NSLog(@"===============================");