Global variable not being retained in Objective C - ios

Question

so I'm trying to get a variable containing the name of a PDF file I wish to open in a UIweb View to show up in a label. I first identify the global variable in a seperate class here:
header:
#import <Foundation/Foundation.h>
extern NSString *PDFNameString;
extern NSString *PDFActualName;
#interface GlobalVars : NSObject
{
}
#property (nonatomic, strong) NSString *PDFActualName;
#property (nonatomic, strong) NSString *PDFNameString;
#end
.m:
#import "GlobalVars.h"
NSString *PDFNameString;
NSString *PDFActualName; //the name of the PDF file
#implementation GlobalVars
{
}
#end
then I have the menu where I have an alert dialog featuring a text field so that the user can input the PDF name:
.h
#import <Foundation/Foundation.h>
#import "GlobalVars.h"
#interface TitleViewController : UIViewController{
NSFileManager *FM1;
}
#property (retain, nonatomic) IBOutlet UIBarButtonItem *OpenPDF;
#property (retain, nonatomic) IBOutlet UIBarButtonItem *ViewPDF;
-(void)OpeningPDF;
-(void)alertView;
#end
.m
#import "TitleViewController.h"
#interface TitleViewController ()
#end
#implementation TitleViewController
UIAlertView * alert;
UITextField *textField;
int StopTheAlerts = 0;
- (void)viewDidLoad
{
[super viewDidLoad];
FM1 = [NSFileManager defaultManager];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)ButtonClicked:(id)sender {
self.OpeningPDF;
}
- (void)dealloc {
[_OpenPDF release];
[_ViewPDF release];
[super dealloc];
}
- (void)OpeningPDF
{
StopTheAlerts = 0;
alert = [[UIAlertView alloc]
initWithTitle:#"Please enter a valid PDF name below:"
message:#"(Please add .PDF on the end!) \n \n"
delegate:self cancelButtonTitle:#"Cancel"
otherButtonTitles:#"ok", nil];
textField = [[UITextField alloc] init];
[textField setBackgroundColor:[UIColor whiteColor]];
textField.delegate = nil;
textField.borderStyle = UITextBorderStyleLine;
textField.frame = CGRectMake(15, 90, 255, 30);
textField.placeholder = #"PDF name";
textField.keyboardAppearance = UIKeyboardAppearanceAlert; //set up an alert box with a text field
[textField becomeFirstResponder];
[alert addSubview:textField];
[alert show];
[alert release];
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
PDFNameString = textField.text; //set the PDF name variable to the name entered
PDFActualName = textField.text;
NSArray *Paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *DocumentDir = [Paths objectAtIndex:0];
NSString *TempFilePath = PDFNameString;
PDFNameString = [DocumentDir stringByAppendingPathComponent:TempFilePath];
if([FM1 fileExistsAtPath: PDFNameString]){
_ViewPDF.enabled = true;
}
else {
while(StopTheAlerts <= 0){
UIAlertView *ErrorAlert = [[UIAlertView alloc]
initWithTitle:#"This file dosn't exist!"
message:#"Please reenter the file name!"
delegate:self cancelButtonTitle:#"OK"
otherButtonTitles: nil];
[ErrorAlert show];
[ErrorAlert release];
StopTheAlerts = 1;
}
}
}
#end
This part all works fine, however, when I switch over the the view that contains the UIWebView to actually view the PDF (I've removed that in this part of the code) it has the old "message sent to deallocated instance 0xdb8fca0" error when I try to assign my global variable to the label containing the PDF name, this error also occurs when trying to get the UIWebView to read the PDF using the other global variable.
.h
#import <UIKit/UIKit.h>
#import "GlobalVars.h"
#interface ViewController : UIViewController
#property (retain, nonatomic) IBOutlet UILabel *PDFNameL;
#end
.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
_PDFNameL.text = PDFActualName;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)dealloc {
[_PDFNameL release];
[super dealloc];
}
#end
If anyone knows a solution to the problem I would be very happy
thanks