Add object to NSMUtable Array Singleton

Question

I have a shared singleton classNSMutableArray [ICGlobals sharedApplianceCount](first time using this pattern so bear with me if ive done something really silly here)

.h

#import <Foundation/Foundation.h>

@interface ICGlobals : NSObject

{

NSMutableArray* applianceCount;
}


@property (nonatomic, retain) NSString *applianceCount;

+ (ICGlobals *)sharedApplianceCount;

@end

.m

#import "ICGlobals.h"

@implementation ICGlobals

static ICGlobals *sharedApplianceCount = nil;


+ (ICGlobals *)sharedUser {
if(sharedApplianceCount == nil){
    sharedApplianceCount = [[super allocWithZone:NULL] init];
  }
return sharedApplianceCount;
}

+ (id)allocWithZone:(NSZone *)zone {
return [self sharedApplianceCount];
}
- (id)copyWithZone:(NSZone *)zone {
return self;
}
@end

In "another view controller" im trying to add the row count of my table view (changeable amount of rows) = self.circuits.count

Having tried this

[[ICGlobals sharedApplianceCount] addObject: self.circuits.count,nil]];

and

[[ICGlobals sharedApplianceCount]   = [[NSMutableArray alloc] init];

[[ICGlobals sharedApplianceCount] addObject: self.circuits.count,Nil]];

I get no visible @interface error saying my singleton class declares the selector

same with

NSNumber* numberOfRows = [NSNumber numberWithInteger:self.circuits.count];

[[ICGlobals sharedApplianceCount]addObject:[NSMutableArray arrayWithObjects:numberOfRows, nil]];

and with

[ICGlobals sharedApplianceCount] = self.circuits.count;

I get expression assignable. Singleton class has been imported.

Are trying to make a singleton ?

Basheer_CAD
– Basheer_CAD

2014-02-23 16:03:52 +00:00
Commented Feb 23, 2014 at 16:03 — Basheer_CAD
– Basheer_CAD, Commented Feb 23, 2014 at 16:03
trying to add objetcs to it in another view controller

JSA986
– JSA986

2014-02-23 16:06:52 +00:00
Commented Feb 23, 2014 at 16:06 — JSA986
– JSA986, Commented Feb 23, 2014 at 16:06

Rafał Sroka · Accepted Answer · 2014-02-23 16:25:03Z

1

You have an inconsistency in your interface declaration. You declare ivar of type NSMutableArray and then a NSString property. Firstable, you don't need to declare ivar, declaring a property does it for you. So your interface should look like:

@interface ICGlobals : NSObject

@property (nonatomic, retain) NSMutableArray *applianceCount;

+ (ICGlobals *)sharedApplianceCount;

@end

Furthermore, you have a naming glitch. You should not use name applianceCount for an array. In general, naming convention of Cocoa suggests that count should be a number (int or NSUInteger). I would change this property name to applianceCounts.

Then, when you initialize your singletone, you can also initialize the array:

+ (ICGlobals *)sharedUser 
{
    if(sharedApplianceCount == nil)
    {
        sharedApplianceCount = [[super allocWithZone:NULL] init];
        sharedApplianceCount.applianceCounts = [[NSMutableArray alloc] init];
    }

    return sharedApplianceCount;
}

Finally, here is how to add data to your singletone's applianceCounts array from view controller.

NSNumber* numberOfRows = [NSNumber numberWithInteger:self.circuits.count];

[[ICGlobals sharedApplianceCount].applianceCounts addObject:numberOfRows];

This should point you to right direction. I don't fully get what you are trying to achieve like I don't understand why you want to have an array there, so if you need further help please let me know in the comments.

I fully recommend you reading about naming conventions. A good start is this article:

Introduction to Coding Guidelines for Cocoa.

edited Feb 23, 2014 at 16:25

answered Feb 23, 2014 at 16:17

Rafał Sroka

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2 Comments

JSA986 Over a year ago

Thank you very much for explaining that to me, first time with singleton and thats a great example. Im storing the row count in an array so I can use this figure for a calculation in another view/s. (and learn about singletons) If theres a more efficent way of doing then I would explore that. Using app dleegate seem frowned upon

JSA986 Over a year ago

Getting: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[ICGlobals sharedApplianceCount]: unrecognized selector sent to class 0x18b330' using the above code?

Basheer_CAD · Accepted Answer · 2014-02-23 16:29:08Z

1

I would recommend some refactoring to your class. First you make the interface like this:

@interface ICGlobals : NSObject
// add the app count but make it private, because you will provide methods to access it
@property (nonatomic, readonly) NSString *applianceCount;

// return ICGlobals instance 
+ (ICGlobals)sharedCounter;

- (NSInteger)count;
- (void)addObject:(id)object;

now in .m file

@implementation ICGlobals

static ICGlobals *sharedApplianceCount = nil;
// this is your method, just changed the name
+ (ICGlobals *)sharedCounter {
if(sharedApplianceCount == nil){
    sharedApplianceCount = [[super allocWithZone:NULL] init];
  }
return sharedApplianceCount;
}

// instance methods goes here 
- (NSInteger)count
{
    return _applicationCount.count;
}

- (void)addObject:(id)object
{
    [_applicationCount addObject:object];
}

Now call [[ICGlobals sharedCount]addObject:object] from any viewController

answered Feb 23, 2014 at 16:29

Basheer_CAD

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2 Comments

JSA986 Over a year ago

This gives me <ICglobals2: 0x17571850> in my log. I have changed @property (nonatomic, readonly) NSString applianceCount; to a mustabel array and + (ICGlobals)sharedCounter; to + (ICGlobals)sharedCounter;

JSA986 Over a year ago

No + (ICGlobals)sharedCounter; needs *, @property (nonatomic, readonly) NSString *applianceCount; I think needs to be Mutable array? [[ICGlobals sharedCount]addObject:object] needs to be [[ICGlobals sharedCounter]addObject:object] Done those but just get <ICGlobals: 0xc1134d0> when logged

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