iOS 5 sdk issue with mutable arrays - iphone

Question

Hello I created a app on iOS 4.3.3 and than downloaded Xcode 4.2.1 and iOS sdk 5. It's a navigation-based application and it has a mutable array for the tableview but it won't create any strings for the array, so i added an object to array in the viewdidload but it is not working! So i added NSlog to the objects in my array and it says null! What should i do?
Here's the viewdidload:
- (void)viewDidLoad
{
[super viewDidLoad];
self.soldc = [NSMutableArray arrayWithCapacity:0];
self.color = [NSMutableArray arrayWithCapacity:0];
appdelegate = (yard_sale_managerAppDelegate *)[[UIApplication sharedApplication] delegate];
appdelegate.object = self;
NSMutableArray *loadi = [[NSMutableArray alloc]initWithCapacity:0];
self.items = loadi;
self.sold = [NSMutableArray arrayWithCapacity:0];
self.prices = [NSMutableArray arrayWithCapacity:0];
alert = [[UIAlertView alloc] initWithTitle:#"Add product" message:#"Enter your product name and price." delegate:self cancelButtonTitle:#"Add" otherButtonTitles:#"Cancel", nil];
[alert addTextFieldWithValue:#"" label:#"name"];
[alert addTextFieldWithValue:#"" label:#"price"];
add = [alert textFieldAtIndex:0];
add.keyboardType = UIKeyboardTypeAlphabet;
add.keyboardAppearance = UIKeyboardAppearanceAlert;
add.autocapitalizationType = UITextAutocapitalizationTypeWords;
add.autocorrectionType = UITextAutocorrectionTypeNo;
add2 = [alert textFieldAtIndex:1];
add2.keyboardType = UIKeyboardTypeNumberPad;
add2.keyboardAppearance = UIKeyboardAppearanceAlert;
add2.autocapitalizationType = UITextAutocapitalizationTypeWords;
add2.autocorrectionType = UITextAutocorrectionTypeNo;
NSLog(#"%i", [color count]);
alert.tag=1;
self.resa = [[UIAlertView alloc] initWithTitle:#"Sale results" message:#"temple" delegate:self cancelButtonTitle:#"Close" otherButtonTitles: nil];
self.items = [NSMutableArray arrayWithContentsOfFile:[self itemsp]];
self.prices = [NSMutableArray arrayWithContentsOfFile:[self pricesp]];
self.sold = [NSMutableArray arrayWithContentsOfFile:[self soldp]];
self.soldc = [NSMutableArray arrayWithContentsOfFile:[self soldcp]];
self.color = [NSMutableArray arrayWithContentsOfFile:[self colorsp]];
if ([self.soldc count]==0) {
}
//self.soldc = [NSMutableArray arrayWithContentsOfFile:[self soldcp]];
self.color = [NSMutableArray arrayWithContentsOfFile:[self colorsp]];
[loadi release];
self.resa.tag = 2;
[self.items addObject:#"chair"];
[self.prices addObject:#"30"];
[self.color addObject:#"0"];
NSLog(#"%#",self.items);
}
If you need more information tell me!
This is the log:
2012-01-08 21:31:13.409 yard sale manager[1152:f803] 0
2012-01-08 21:31:13.411 yard sale manager[1152:f803] (null)
edit: read this its important!!!!!
a lot of people didn't notice that piece of code:
[self.items addObject:#"chair"];
[self.prices addObject:#"30"];
[self.color addObject:#"0"];
NSLog(#"%#",self.items);

Answer 1

This line
self.color = [NSMutableArray arrayWithCapacity:0];
instantiates and assigns an empty array, you then do not add anything to it therefore the 0 count.
Then this line
self.items = [NSMutableArray arrayWithContentsOfFile:[self itemsp]];
is probably the cause. Does [self itemsp] return a valid file path that points to a file that can be parsed into an NSArray.
There are also a lot of other issues with this code.
Update
This line
self.items = [NSMutableArray arrayWithContentsOfFile:[self itemsp]];
must be returning nil.
Confirm by adding this line straight after it
NSLog(#"%#", self.items);
How can I make this assumption
The reason I am making this assumption is because you are getting (null). When you call addObject: on nil you will get nil returned and it is a no-op. As you can see from this snippet
NSMutableArray *myArray = nil;
[myArray addObject:#"Test"];
NSLog(#"%#", myArray);
// => 2012-01-08 20:54:04.708 Untitled[4199:707] (null)
Just because myArray holds a pointer to an NSMutableArray it does not mean that you actually have one.
Therefore the last time you assign to self.items is in:
self.items = [NSMutableArray arrayWithContentsOfFile:[self itemsp]];
which means [NSMutableArray arrayWithContentsOfFile:[self itemsp]] is returning nil

Answer 2

Given that NSLog(#"%#",self.items); prints (null) it follows that the self.items NSMutableArray is never created. The only way that could happen is if
self.items = [NSMutableArray arrayWithContentsOfFile:[self itemsp]];
returns nil, that is does not read anything, probably because there is nothing at the path.
NSLog self.items right after the statement:
self.items = [NSMutableArray arrayWithContentsOfFile:[self itemsp]];
If you are trying to write to the app bundle that won't work, you need to write a directory such as the sandboxed Documents directory.