Question

I used NSFileManager to read and write in a file. It works fine, but I cannot view the data written in that file, it works with simulator but doesn’t work in the iPhone.
viewcontroller.h:

#import <MessageUI/MessageUI.h>
#import <MessageUI/MFMailComposeViewController.h>

@interface next : UIViewController <MFMailComposeViewControllerDelegate,UITextViewDelegate,UIAlertViewDelegate>{
    IBOutlet UIButton *read;

}
@property(nonatomic,retain)IBOutlet UITextView *txt;
@property (nonatomic, retain) IBOutlet UILabel *message;


-(IBAction)showPicker:(id)sender;
-(void)displayComposerSheet;
-(void)launchMailAppOnDevice;

@end
 viewcontroller.m:
-(void) viewDidLoad {
    self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"mainbg.png"]];
    NSFileManager *filemgr;

    filemgr = [NSFileManager defaultManager];

    NSString *path = [[NSBundle mainBundle] pathForResource:@"help" ofType:@"txt"];
    if ([filemgr fileExistsAtPath:path ] == YES)
        NSLog (@"File exists");
    else
        NSLog (@"File not found");


    NSString *fileName = [[NSBundle mainBundle] pathForResource:@"help" ofType:@"txt"];

    NSString *content1 = [[NSString alloc] initWithContentsOfFile:fileName encoding:NSUTF8StringEncoding error:nil];
    //use simple alert from my library (see previous post for details)
    //NSArray *lines = [content1 componentsSeparatedByString:@"\n"];
    txt.text = content1;
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"file"
                                                    message:content1
                                                   delegate:self
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles: nil];


    [alert show];
    NSLog(@"content1");
    [content1 release];
    [alert release];
    [super viewDidLoad];    


}
//mailing
-(IBAction)showPicker:(id)sender
{
    Class mailClass = (NSClassFromString(@"MFMailComposeViewController"));
    if (mailClass != nil)
    {
        // We must always check whether the current device is configured for sending emails
        if ([mailClass canSendMail])
        {
            [self displayComposerSheet];
        }
        else
        {
            [self launchMailAppOnDevice];
        }
    }
    else
    {
        [self launchMailAppOnDevice];
    }
}

-(void)displayComposerSheet 
{
    MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init];
    picker.mailComposeDelegate = self;

    [picker setSubject:@"Hello friends!"];


    // Set up recipients
    NSArray *toRecipients = [NSArray arrayWithObject:@"[e-mail]"]; 
    NSArray *ccRecipients = [NSArray arrayWithObjects:@"[e-mail]", @"[e-mail]", nil]; 
    NSArray *bccRecipients = [NSArray arrayWithObject:@"[e-mail]"]; 

    [picker setToRecipients:toRecipients];
    [picker setCcRecipients:ccRecipients];  
    [picker setBccRecipients:bccRecipients];

    // Attach an image to the email
    NSString *path = [[NSBundle mainBundle] pathForResource:@"help" ofType:@"txt"];
    NSData *myData = [NSData dataWithContentsOfFile:path];
    [picker addAttachmentData:myData mimeType:@"file/txt" fileName:@"help"];

    // Fill out the email body text
    NSString *emailBody = @"hii how r u !";
    [picker setMessageBody:emailBody isHTML:NO];

    [self presentModalViewController:picker animated:YES];
    [picker release];
}


// Dismisses the email composition interface when users tap Cancel or Send. Proceeds to update the message field with the result of the operation.
- (void)mailComposeController:(MFMailComposeViewController*)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error 
{   
    message.hidden = NO;
    // Notifies users about errors associated with the interface
    switch (result)
    {
        case MFMailComposeResultCancelled:
            message.text = @"Email: Canceled";
            break;
        case MFMailComposeResultSaved:
            message.text = @"Email: Saved";
            break;
        case MFMailComposeResultSent:
            message.text = @"Email: Sent";
            break;
        case MFMailComposeResultFailed:
            message.text = @"Email: Failed";
            break;
        default:
            message.text = @"Email: Not Sent";
            break;
    }
    [self dismissModalViewControllerAnimated:YES];
}


#pragma mark -
#pragma mark Workaround

// Launches the Mail application on the device.
-(void)launchMailAppOnDevice
{
    NSString *recipients = @"mailto:[e-mail]?cc=[e-mail],@[e-mail]&subject=Hello !";
    NSString *body = @"&body=hello how r u !";

    NSString *email = [NSString stringWithFormat:@"%@%@", recipients, body];
    email = [email stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:email]];
}

Answer 1

Can you use the real-time debugger ?
1) set break points to check the variables/path
2) create some try-catch blocks to see if there’s an ‘unhandled’ exception somewhere