Question

So I’m creating an array called fruits which I would like to share between multiple views. This is my code:

#import <foundation/Foundation.h>
@interface MyManager : NSObject {
    NSMutableArray *fruits;
}
@property (nonatomic, retain) NSMutableArray *fruits;
+ (id)sharedManager;
@end

#import "MyManager.h"
static MyManager *sharedMyManager = nil;
@implementation MyManager
@synthesize fruits;
#pragma mark Singleton Methods
+ (id)sharedManager {
    @synchronized(self) {
        if (sharedMyManager == nil)
            sharedMyManager = [[self alloc] init];
    }
    return sharedMyManager;
}
- (id)init {
    if ((self = [super init])) {
        fruits = [[NSMutableArray alloc] init];
    }
    return self;
}
-(void) dealloc{
    self.fruits = nil;
    [super dealloc];
}
@end

Now I’m using the following code so that I can use workouts in the new view

#import "MyManager.h"
@interface Chest : UIViewController {
    IBOutlet MyManager *fruits;
}
@property (nonatomic, retain) IBOutlet MyManager *fruits;
-(IBAction) goToList: (id) sender;
@end

When a button is clicked, goToList is called, and I populate my array, fruits

#import "Chest.h"
@implementation Chest
@synthesize fruits;
-(IBAction) goToList:(id)sender{
    MyManager *fruits = [MyManager sharedManager];
    NSString *filePath;
    NSString *fileContents;
    filePath = [[NSBundle mainBundle] pathForResource:@"chest_strength" ofType:@"csv"];
        fileContents = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
        fruits = [fileContents componentsSeparatedByString:@"\n"];
}

When I output the elements of *fruits in this view, everything works fine. Now when I try to access this same variable in the other view, it says the array is null. Here’s the code for the second view:

@interface List : UIViewController {
    IBOutlet MyManager *fruits;
}
@property (nonatomic, retain) IBOutlet MyManager *fruits;
@end

#import "List.h"
#import "MyManager.h"
@implementation List
@synthesize fruits
NSLog(@"%@", fruits);  //This is the part that isn't displaying correctly.  I'm getting a null here

So my question is, how do I do this so that I can get the array fruits that I populated in Chest and use it in List so that I can display the contents of the array in that view?

Thank you to everybody who answers. This problem is seriously bogging me down and I need to finish this project ASAP. Much appreciated.

Answer 1

You’ve changed a few things in this question but the fundamental problem remains: the array is a property of your singleton, and you are not treating it as such.

Whenever you refer to the array, outside of the singleton, do it like this:

[MyManager sharedManager].fruits

If you are accessing it frequently, you can create a local ivar, but you certainly wouldn’t have it as an IBOutlet, which you are doing in your last code sample. How is that ever going to be set?