如何查看通过Xcode中的代码写入文件的数据？

问题描述

| 我使用NSFileManager读取和写入文件。它可以正常工作，但是我无法查看写入该文件的数据，它可以与模拟器一起使用，但不能在iPhone中使用。 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:@\"[email protected]\"]; 
    NSArray *ccRecipients = [NSArray arrayWithObjects:@\"[email protected]\",@\"[email protected]\",nil]; 
    NSArray *bccRecipients = [NSArray arrayWithObject:@\"[email protected]\"]; 

    [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:[email protected][email protected],@[email protected]&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]];
}

    

解决方法

        您可以使用实时调试器吗？ 1）设置断点以检查变量/路径 2）创建一些try-catch块，以查看某处是否存在“未处理的”异常