Question

I save pieces of data from my Cocoa application into a text file. The text file contains information as shown:

foo1 -> foo2
blah -> lwjef
hi -> bye
hello -> goodbye

Now the first part of each row is given by the user, but I need to get the part of each row after the ->. For example, if the user enters foo1, I want to output foo2 after parsing the text file. Does anyone know how to do this?

Answer 1

Parse once:

NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
NSArray *lines = [string componentsSeparatedByCharactersInSet: [NSCharacterSet newlineCharacterSet]];
for (NSString *line in lines) {
    NSArray *values = [line componentsSeparatedByString:@" -> "];
    if ([values count] != 2) {
        continue;
    }
    [dictionary setObject:[values objectAtIndex:1] forKey:[values objectAtIndex:0]];
}

Then query for keys:

NSString *input = @"foo1";
NSString *answer = [dictionary objectForKey:input]; //@"foo2"

---

However, if the data originally came from your own application in the first place you should probably do this, instead of a custom (and insecure) string format:

//For saving:
[dictionary writeToFile:filePath atomically:YES];
//For loading:
NSDictionary *dictionary = [NSDictionary dictionaryWithContentsOfFile:filePath];