App doesn't save before going to background - iphone

Question

I want to save some texts in textfields whenever the user goes to the background i think i wrote everything correctly since i followed many question/answers. However when I close my app my app doesn't save the text or even create a plist so when i reopen it, the textfields are empty. Here is the code:
RootViewController.h:
#interface RootViewController: UIViewController <UITextFieldDelegate> {
UITextField *textField1;
UITextField *textField2;
UITextField *textField3;
UITextField *textField4;
}
#property (nonatomic, retain) UITextField *textField1, *textField2, *textField3, *textField4;
#end
RootViewController.m:
#import "RootViewController.h"
#implementation RootViewController
#synthesize textField1, textField2, textField3, textField4;
...
- (UILabel*)addNewLabel:(NSString*)_text
{
//Initializing TextViews
}
....
- (NSString *) saveFilePathB
{
NSString *path = #"/Applications/AppDissassembler.app/Cache/savefileb.plist";
return path;
}
- (void)loadView {
self.view = [[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease];
self.view.backgroundColor = [UIColor whiteColor];
//creating textfields
self.textField1 = [self addNewTextfield:60:80:175:true:#"Binary Name Here":1];
self.textField2 = [self addNewTextfield:60:145:200:true:#"Offset Here (0xOffset)":2];
self.textField3 = [self addNewTextfield:75:210:175:false:nil:3];
self.textField4 = [self addNewTextfield:75:310:175:false:nil:4];
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
NSArray *values = [[NSArray alloc] initWithObjects:self.textField1.text,self.textField2.text,self.textField3.text,self.textField4.text,nil];
NSFileHandle *fout1;
[[NSFileManager defaultManager] createFileAtPath:[self saveFilePathB] contents:nil attributes:nil];
//open output file for writing
fout1 = [NSFileHandle fileHandleForWritingAtPath:[self saveFilePathB]];
[values writeToFile:[self saveFilePathB] atomically:YES];
[values release];
}
- (void)viewDidLoad
{
NSString *myPath = [self saveFilePathB];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:myPath];
if (fileExists)
{
NSArray *values = [[NSArray alloc] initWithContentsOfFile:myPath];
self.textField1.text = [values objectAtIndex:0];
self.textField2.text = [values objectAtIndex:1];
self.textField3.text = [values objectAtIndex:2];
self.textField4.text = [values objectAtIndex:3];
[values release];
}
UIApplication *myApp = [UIApplication sharedApplication];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(applicationDidEnterBackground:) name:#"UIApplicationDidEnterBackgroundNotification" object:myApp];
[super viewDidLoad];
}
- (void)dealloc {
[textField1 release];
[textField2 release];
[textField3 release];
[textField4 release];
[super dealloc];
}
#end
If I change this:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(applicationDidEnterBackground:) name:#"UIApplicationDidEnterBackgroundNotification" object:myApp];
to this:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(applicationDidEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:myApp];
I get an error which says that UIApplicationDidEnterBackgroundNotification wasn't declared.

Answer 1

It wont run in method you try, so in UIApplicationDidEnterBackground delegate. All you have to do is handle your process while going into background with beginBackgroundTaskWithExpirationHandler. See this topic: topic

Answer 2

The second version you tried, where UIApplicationDidEnterBackgroundNotification is an identifier not a literal string, is the correct way to use this feature. It should be defined in UIApplication.h.
You say you are compiling on the iPhone itself, so it sounds like the development environment you have there is lacking this definition. I haven't tried that myself, so can't be sure.
Once you have got past the compilation error I would recommend to use NSLog to see where your code has got to, because this is easier than looking for the file to be created.