Managing multiple NSArrays on a different UIViewController? - ios

Question

is it possible to manage multiple NSArrays on a different View Controller?
Here's my example:
I am currently working with two View Controllers:
TableViewController serves as a main menu. I've set up multiple UIButtons, each has a tag and when the user presses a button, it'll take them to the TableOneViewController.
In TableOneViewController, so far I've set up an UIImageView and a UIButton, every time the user presses the button, the UIImageView changes the image through an NSArray.
I want to use the tags on the TableViewController to manage the NSArrays of the TableOneViewController. Is this possible? So far, my code is not working.
Here's the code. Thanks!
TableViewController.m
- (IBAction)tableSelection:(id)sender
{
TableOneViewController *TOVC = [self.storyboard instantiateViewControllerWithIdentifier:#"TableOneViewController"];
if ([sender tag] == 1) {
[[NSUserDefaults standardUserDefaults] setObject:TOVC.numOne forKey:#"num"];
[[NSUserDefaults standardUserDefaults] setObject:#"1.png" forKey:#"num2"];
}
if ([sender tag] == 2) {
[[NSUserDefaults standardUserDefaults] setObject:TOVC.numTwo forKey:#"num"];
[[NSUserDefaults standardUserDefaults] setObject:#"2.png" forKey:#"num2"];
}
if ([sender tag] == 3) {
[[NSUserDefaults standardUserDefaults] setObject:TOVC.numThree forKey:#"num"];
[[NSUserDefaults standardUserDefaults] setObject:#"3.png" forKey:#"num2"];
}
[self presentViewController:TOVC animated:YES completion:nil];
}
TableOneViewController.m
- (IBAction)nextButton:(id)sender
{
int index = tableCounter++ % [self.numOne count];
self.num.image = self.numOne[index];
}
- (void)viewDidLoad
{
self.num.image = [UIImage imageNamed:[[NSUserDefaults standardUserDefaults] objectForKey:#"num"]];
self.num2.image = [UIImage imageNamed:[[NSUserDefaults standardUserDefaults] objectForKey:#"num2"]];
[super viewDidLoad];
tableCounter = 10;
self.numOne = [NSArray arrayWithObjects:
[UIImage imageNamed:#"2.png"],
[UIImage imageNamed:#"3.png"],
[UIImage imageNamed:#"4.png"],
[UIImage imageNamed:#"5.png"],
[UIImage imageNamed:#"6.png"],
[UIImage imageNamed:#"7.png"],
[UIImage imageNamed:#"8.png"],
[UIImage imageNamed:#"9.png"],
[UIImage imageNamed:#"10.png"],
[UIImage imageNamed:#"1.png"],
nil];
self.numTwo = [NSArray arrayWithObjects:
[UIImage imageNamed:#"20.png"],
[UIImage imageNamed:#"30.png"],
[UIImage imageNamed:#"40.png"],
[UIImage imageNamed:#"50.png"],
[UIImage imageNamed:#"60.png"],
[UIImage imageNamed:#"70.png"],
[UIImage imageNamed:#"80.png"],
[UIImage imageNamed:#"90.png"],
[UIImage imageNamed:#"100.png"],
[UIImage imageNamed:#"10.png"],
nil];
self.numThree = [NSArray arrayWithObjects:
[UIImage imageNamed:#"200.png"],
[UIImage imageNamed:#"300.png"],
[UIImage imageNamed:#"400.png"],
[UIImage imageNamed:#"500.png"],
[UIImage imageNamed:#"600.png"],
[UIImage imageNamed:#"700.png"],
[UIImage imageNamed:#"800.png"],
[UIImage imageNamed:#"900.png"],
[UIImage imageNamed:#"1000.png"],
[UIImage imageNamed:#"100.png"],
nil];
}

Answer 1

The problem is that you pass the array before presenting the view controller (viewDidLoad hasn't be called yet), then you present it, but you initialize numOne (and the other arrays) in viewDidLoad. I suggest to use lazy initialization, here's the example for numOne, write the same for the other two arrays:
- (NSArray*) numOne
{
if(!_numOne)
{
_numOne= [NSArray arrayWithObjects:
[UIImage imageNamed:#"2.png"],
[UIImage imageNamed:#"3.png"],
[UIImage imageNamed:#"4.png"],
[UIImage imageNamed:#"5.png"],
[UIImage imageNamed:#"6.png"],
[UIImage imageNamed:#"7.png"],
[UIImage imageNamed:#"8.png"],
[UIImage imageNamed:#"9.png"],
[UIImage imageNamed:#"10.png"],
[UIImage imageNamed:#"1.png"],
nil];
}
return _numOne;
}
However this is not the purpose of NSUserDefaults, I consider this approach bad design. It's better if you keep an ivar in TableOneViewController that points to one of the three arrays (same for the image name).
Edit
This is how I would implement the mechanism: an additional property that points to one of the three arrays in TableOneViewController:
#property (nonatomic, weak) NSArray* currentArray;
This pointer should point to the correct array, according to the tag of the sender that triggered tableSelection: :
// TableViewController
- (IBAction)tableSelection:(id)sender
{
TableOneViewController *TOVC = [self.storyboard instantiateViewControllerWithIdentifier:#"TableOneViewController"];
switch([sender tag]) {
case 1:
TOVC.currentArray= TOVC.numOne;
break;
case 2:
TOVC.currentArray= TOVC.numTwo;
break;
case 3:
TOVC.currentArray= TOVC.numThree;
break;
default:
return;
}
[self presentViewController:TOVC animated:YES completion:nil];
}
// TableOneViewController
- (IBAction)nextButton:(id)sender
{
int index = tableCounter++ % [self.currentArray count];
self.num.image = self.currentArray[index];
}

Answer 2

It doesn't work because
TableOneViewController *TOVC = [self.storyboard instantiateViewControllerWithIdentifier:#"TableOneViewController"];
creates a completely new instance of your TableOneViewController. I would use a singleton retaining the arrays and any other info I need as a single access point during the execution of my program.