Searching Through a TextFile - Cocoa

Question

How would I type up a code that searches through a text file from a given directory. I want the search word to be "password123" and if it contains that, then it will proceed onto the next step, if not it will give an error message.

Answer 1

Try this function;

ETA

Okay, I'm an idiot and I typed in code without trying it out first.

This works. I've also got a simple Xcode project which works with this which you can download to try for yourself if I've typed anything wrong in here.

    // Get the URL for the Password.txt file on the desktop.
    NSURL *fileURL = [NSURL fileURLWithPath:[@"~/Desktop/Password.txt" stringByExpandingTildeInPath]];

    // Read the contents of the file into a string.
    NSError *error = nil;
    NSString *fileContentsString = [NSString stringWithContentsOfURL:fileURL 
                                                            encoding:NSUTF8StringEncoding 
                                                               error:&error];

    // Make sure that the file has been read, log an error if it hasn't.
    if (!fileContentsString) {
        NSLog(@"Error reading file");
    }

    // Create the string to search for
    NSString *password = @"Password123";

    // Search the file contents for the given string, put the results into an NSRange structure
    NSRange result = [fileContentsString rangeOfString:password];

    // -rangeOfString returns the location of the string NSRange.location or NSNotFound.
    if (result.location == NSNotFound) {
        // Password not found. Bail.
        NSLog(@"Password not found in file");
        return;
    }
    // Continue processing
    NSLog(@"Password found in file");    
}

Answer 2

To read a text file:

NSString *path = ...;
NSError *error;
NSString *stringFromFileAtPath = [[NSString alloc]
                                      initWithContentsOfFile:path
                                      encoding:NSUTF8StringEncoding
                                      error:&error];
if (stringFromFileAtPath == nil) {
    // an error occurred
    NSLog(@"Error reading file at %@\n%@",
              path, [error localizedFailureReason]);
    // implementation continues ...

Taken from the Apple docs found here.

You could use

NSString rangeOfString: 

to search for your string.
More about that here: Apple Documentation: Searching Strings

Answer 3

If you want to stick to Cocoa, then NSScanner is your friend.

If you don't bother using plain unix api, you can use:

int match = system("grep -q password123 pathToMyfile");

and check whether match is 0, in which case a match has been found.