Objective-C, get string from text file?

Question

I know there are a few different ways to find text in file, although I haven't found a way to return the text after the string I'm searching for. For example, if I was to search file.txt for the term foo and wanted to return bar, how would I do that without knowing it's bar or the length?

Here's the code I'm using:

if (!fileContentsString) {
    NSLog(@"Error reading file");
}

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

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

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

JeanLuc · Accepted Answer · 2012-07-16 10:03:29Z

1

you could use [NSString substringFromIndex:]

if (result.location == NSNotFound) 
{
    // foo not found. Bail.
    NSLog(@"foo not found in file");
    return;
}    
else    
{
    int startingPosition = result.location + result.length;
    NSString* foo = [fileContentsString substringFromIndex:startingPosition]        
    NSLog(@"found foo = %@",foo);  
}

edited Jul 16, 2012 at 10:03

answered Jul 16, 2012 at 6:47

JeanLuc

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6 Comments

Joe Habadas Over a year ago

thank you - i'll try this out. Is there any advantage/disadvantage from xingzhi.sg's example? just curious.

JeanLuc Over a year ago

my solution is easier for that task (especially if you're not familiar with regex). AND it just needs iOS 2.0 or OS X 10.0, so you don't need to carry an extra library with your project

Joe Habadas Over a year ago

imageKey must be iOS specific?; I'm try to create this for OS X, is there an equivalent for that?

JeanLuc Over a year ago

sorry imageKey was a local variable in my project. i edited my answer it should be your local variable fileContentsString

Joe Habadas Over a year ago

okay, I understand. The problem now is that anything after bar is shown also. for example foo bar is the string will result in bar is the string. how do I only show bar?

|

xingzhi.sg · Accepted Answer · 2012-07-16 06:31:12Z

1

You might want to use RegexKitLite and perform a regex look up:

NSArray * captures = [myFileString componentsMatchedByRegex:@"foo\\s+(\\w+)"];
NSString * wordAfterFoo = captures[1];

Not test though.

answered Jul 16, 2012 at 6:31

xingzhi.sg

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2 Comments

Joe Habadas Over a year ago

I get an error on NSString * wordAfterFoo = captures[1]; -- Subscript requires size of interface NSArray, which is not constant in non-fragile ABI

xingzhi.sg Over a year ago

oops... should be [captures objectAtIndex:1];

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