Sorting array of custom objects in Objective-C

Question

I have two classes namely ViewController and BViewController. The BViewController class has properties name, address, and rating.

Below is the code for ViewController.m

How do I go about arranging objects in the array such that they are ordered by rating ascending? Additionally, how do I display them in a view?

- (void)viewDidLoad {

        [super viewDidLoad];

    BViewController *b=[[BViewController alloc]init];
        b.name=@"x";
        b.address=@"bangalore";
        b.rating=@6;

    BViewController *c=[[BViewController alloc]init];
        c.name=@"y";
        c.address=@"bangalore";
        c.rating=@5;

    BViewController *d=[[BViewController alloc]init];
        d.name=@"z";
        d.address=@"bangalore";
        d.rating=@7;

    BViewController *e=[[BViewController alloc]init];
        e.name=@"abc";
        e.address=@"bangalore";
        e.rating=@4;

    BViewController *f=[[BViewController alloc]init];
        f.name=@"xyz";
        f.address=@"bangalore";
        f.rating=@8;
     }

The Mach System · Accepted Answer · 2017-02-22 00:50:26Z

3

Apple has an API to do what you want in an elegant way:

NSMutableArray *yourArray = [NSMutableArray arrayWithObjects:b, c, d, e ,f, nil];
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"rating" ascending:YES];
[yourArray sortUsingDescriptors:@[sortDescriptor]];

Your array has now been sorted nicely.

answered Feb 22, 2017 at 0:50

The Mach System

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Comments

halfer · Accepted Answer · 2020-01-13 23:15:46Z

1

Your array

NSMutableArray *arrMain = [NSMutableArray arrayWithObjects:b, c, d, e ,f, nil];

Now sort based on rating key

NSArray *arrResult;
arrResult = [arrMain sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
    NSNumber *first = [(BViewController*)a rating];
    NSNumber *second = [(BViewController*)b rating];

    NSComparisonResult result =  [first compare:second];
    return  result;
}];

This is tested.

edited Jan 13, 2020 at 23:15

halfer

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answered Feb 14, 2017 at 7:02

Manann Sseth

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4 Comments

taj Over a year ago

can u tell me what am suppose to take in storyBoard like textField or label to display the results,am new so am not getting how it goes!

Manann Sseth Over a year ago

@taj For Input, take UITextfields. UIButton for Sort Array Hit & UILabel to display result values.

taj Over a year ago

hey, can u tell me how can i see output on console? because if i put NSLog(@"%@",arrResult); am getting some output like "<BViewController: 0x60800002ede0>", "<BViewController: 0x60800002f400>", "<BViewController: 0x60800002fa40>", "<BViewController: 0x60800002f9e0>", "<BViewController: 0x60800002fde0>" am not getting it why it is coming this way

Larme Over a year ago

@taj Because when you do NSLog(@"%@", b), that's what you'll get. To have a "meaningful" log, override -(NSString *)description method of BViewController, with something like

return [NSString stringWithFormat:@"<%@ %p> name: %@, address: %@, rating: %@", [self class], self, _name, _address, _rating];

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