How to sort a custom NSArray?

Question

I have a class officeSupply

@interface OfficeSupply : NSObject

@property (nonatomic, strong) NSString *itemName;
@property (nonatomic) int total;
@property (nonatomic) int price;
@property (nonatomic) int quantity;
@property (nonatomic, strong) UITextField *quantityText;
@property (nonatomic, strong) UIImage *itemPic;

-(id)initWithName:(NSString *)itemName total:(int)total price:(int)price quantity:(int)quantity picture:(UIImage *)itemPic;

@end

And in my view I have

 OfficeSupply *item1 = [[OfficeSupply alloc] initWithName:@"Stapler" total:0 price:50 quantity:0 picture:[UIImage imageNamed:@"stapler.jpg"]];
OfficeSupply *item2 = [[OfficeSupply alloc] initWithName:@"Paper" total:0 price:150 quantity:0 picture:[UIImage imageNamed:@"101291.jpg"]];
OfficeSupply *item3 = [[OfficeSupply alloc] initWithName:@"Pen" total:0 price:45 quantity:0 picture:[UIImage imageNamed:@"pen.jpg"]];
_items =[NSArray arrayWithObjects:item1, item2, item3, nil];

[_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

I've looked up the problem already but haven't been able to solve my problem.

The last line is supposed to sort it but I don't know why it won't.

I just want to sort them by name.. Any ideas?

It sorts the array just fine. But you never assign that sorted array to anything -- it just falls on the floor. — Hot Licks
– Hot Licks, Commented May 28, 2013 at 22:06

Wain · Accepted Answer · 2013-05-28 22:05:55Z

3

You can't edit an NSArray because it's immutable so you need to do:

_items = [_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

answered May 28, 2013 at 22:05

Wain

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lukestringer90 · Accepted Answer · 2013-05-28 22:25:49Z

The call to sortedArrayUsingDescriptors: returns an NSArray instance, which is the sorted representation of the instance you call the method on. So:

NSArray *sortedItems = [_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

You could also simply further by using literal syntax for your array of sort descriptors.

NSArray *sortedItems = [_items sortedArrayUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

If you want to keep mutating the _items NSArray instance then create is as an NSMutableArray to start with.

// Make sure _items instance variable is declared as an NSMutableArray    
_items =[NSMutableArray arrayWithObjects:item1, item2, item3, nil];

[_items sortUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

Saraswati · Accepted Answer · 2013-05-29 05:09:55Z

0

TAke _items as NSMutableArray...

NSArray *sortedArray;
sortedArray=[_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

[_items removeAllObjects];
[_items addObjectsFromArray:sortedArray];

answered May 29, 2013 at 5:09

Saraswati

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