如何從文本文件中的特定位置使用iphone讀取文本？

Question

我是新來的iphone請幫助我，我想從文本文件使用iphone中讀取文本現在我能夠從txtfile中讀取文本，但我的問題是（在txtfile中保存了一些數據，例如「welcome to webapps」想要只讀webapp字符串） 通過使用此代碼，我從txtfile.please中讀取所有數據，給出任何想法只讀取指定的文本。

-(NSString *)readFile:(NSString *)fileName { 
    NSString *filePath = [[NSBundle mainBundle] pathForResource:fileName ofType:@"txt"]; 
    NSData *myData = [NSData dataWithContentsOfFile:filePath]; 
    NSString *str,*docStr; 

    if (myData) { 
     str = [[NSString alloc] initWithData:myData encoding:NSASCIIStringEncoding]; 

     } 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 

    // the path to write file 
    NSString *appFile = [documentsDirectory stringByAppendingPathComponent:fileName]; 
    NSError *error = nil; 
    BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:appFile]; 
    if(fileExists) 
    { 
     NSLog(@"file exist in document"); 
     NSData *myData1 = [NSData dataWithContentsOfFile:appFile]; 
     if (myData1) { 
      docStr = [[NSString alloc] initWithData:myData1 encoding:NSASCIIStringEncoding]; 

     } 
    } 
    else { 
     NSLog(@"file does not exist"); 

     BOOL success = [str writeToFile:appFile atomically:YES encoding:NSUTF8StringEncoding error:&error]; 
     if (!success) { 
      NSLog(@"Error: %@", [error userInfo]); 
     } 
     else { 
      NSLog(@"File write is successful"); 

     } 
     NSData *myData1 = [NSData dataWithContentsOfFile:appFile]; 
     if (myData1) { 
      docStr = [[NSString alloc] initWithData:myData1 encoding:NSASCIIStringEncoding]; 

     } 
    } 


    return docStr; 
} 

Answer 1

NSString *mystring=[docstr substringFromIndex:11]; 

在MyString中，你將有「的webapps」