Adding a NSMutableArray to project & access that same NSMutableArray in another class - ios

Question

I am having some trouble trying to share a NSMutableArray of Strings to another class. I have a tableView that is populated with Strings that I would like to add to a NSMutableArray. Then use that SAME NSMutableArray in another ViewController
I have created a class with the subclass of NSMutableArray
.h
#import <Foundation/Foundation.h>
#interface HYServicesMArray : NSMutableArray
#property (nonatomic, weak)NSMutableArray * arrServicesUserChoice;
#end
.m
#import "HYServicesMArray.h"
#implementation HYServicesMArray
#dynamic arrServicesUserChoice;
#end
I am trying to add elements to this NSMutableArray from a tableView didSelectRowAtIndexPath:
.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryCheckmark;
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
NSLog(#"You have selected: %#",cell.textLabel.text);
// add cell.textLabel.text to arrServicesUserChoice
// Tried the code below but causes my app to crash
arrServicesUserChoice = [[NSMutableArray alloc]init];
[arrServicesUserChoice addObject:cell.textLabel.text];
}
How ever I am unable to add elements to the arrServicesUserChoice. I am stuck please help! Thank you in advance!

Answer 1

YOu declared a mutable array, and the code you used to add returns an array, but it dont add anyting. you have to add the objects like:
[arrAvaialbleServicesList addObject:cell.textlabel.text];
After this, your mutable array will have the added data
or you can declare another array, and do it your way"
NSArray *test=[arrAvaialbleServicesList arrayByAddingObject:cell.textLabel.text];
after this, the new array will have the array with added data.

Answer 2

I think you should change
#dynamic arrServicesUserChoice;
To
#synthesize arrServicesUserChoice;

Answer 3

The original initialization to MutableArray does nothing really and does not specify arrAvalabelServiceList as Mutable - arrayByAddingObject creates a brand new instance which is NSArray, NOT NSMutableArray
arrAvaialbleServicesList = [[NSMutableArray alloc]init];
[arrAvaialbleServicesList arrayByAddingObject:cell.textLabel.text];
You are however not assigning this new instance to anything, if you did:
arrAvaialbleServicesList = [arrAvaialbleServicesList arrayByAddingObject:cell.textLabel.text];
You would at least get a handle to the new NSArray instance.
What you should probably to is to create your list when you setup the table:
arrAvaialbleServicesList = [[NSMutableArray alloc]init];
The on your didSelect you would just add the text to the list:
NSString *selected = [NSString stringWithString:cell.textLabel.text];
[arrAvaialbleServicesList addObject:selected];
or something close to this then you would add something to your list whenever you select a row in the table.

Answer 4

What you try to create is a kind of public static var correct? i think the better way to do that is creating an Class that can handle your MutableArray object. Doing her as a singleton class is a good way to guarantee that you will not create another instance of your object and lost your MutableArray. Here is a sample:
HYServicesMArray.h
#import <Foundation/Foundation.h>
#interface HYServicesMArray : NSObject
#property (nonatomic, strong) NSMutableArray *arrServicesUserChoice;
+ (HYServicesMArray *) instance;
#end
HYServicesMArray.m
#import "HYServicesMArray.h"
#implementation HYServicesMArray
+ (HYServicesMArray *)instance
{
static HYServicesMArray *_ServicesMArray = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_ServicesMArray = [[self alloc] init];
});
return _ServicesMArray;
}
-(id)init {
self.arrServicesUserChoice = [[NSMutableArray alloc] init];
return self;
}
#end
And the application on your didSelectRowAtIndexPath method:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryCheckmark;
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
NSLog(#"You have selected: %#",cell.textLabel.text);
[[HYServicesMArray instance].arrServicesUserChoice addObject:cell.textLabel.text];
}

Answer 5

You should make it #synthesized and dereference the property as self.arrServicesUserChoice. (You can leave the self away only in Swift.)
This should compile:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryCheckmark;
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
NSLog(#"You have selected: %#",cell.textLabel.text);
self.arrServicesUserChoice = [[NSMutableArray alloc] init];
[self.arrServicesUserChoice addObject:cell.textLabel.text];
}

Answer 6

You do not need to declare it #dynamic, You need to #synthesize it. If you don't want to #synthesize it then use self. You can check the difference between here between these two here.
#synthesize vs #dynamic, what are the differences?
If you want to use this same array in another class then you should declare a property in that class and pass this class's array to another class using segue.