Objective-C, making an NSArray of each unique character in an NSString - objective-c

Question

I've searched around and found several questions answered which were similar to this one, but not exactly the same and I have not been able to get the sample code given in those answers to work for me. I admit this could very likely be my ignorance of Objective-C getting in the way. My situation is this:
I have an NSString from a text file which contains a variety of characters. The length of the string can vary based on what is in the text file. I need to make an array giving each individual character in the string.
I've tried 5 different approaches to the problem (three of them from answers on this site) but each effort I've made to do this has resulted in a) segmentation faults I couldn't track down, b) the array remaining NULL while giving compiler warnings, or c) the array remaining NULL without compiler warnings. In case it matter's, I'm using: gcc -framework Foundation -std=c99 TestCode.m -o TestProgram
Sorry there's no specific code here because I've deleted all my failed efforts in frustration. I guess there's a reason why you shouldn't try to learn a programming language at the same time as trying to learn a new subject that you are applying the language to :)
Would anyone be so helpful as to give me a couple of snippets to work with here?

Answer 1

This is how you would do it.
Read the contents of the file into a NSSString
Enumerate all all the characters
Add them to a NSMutableSet
Get allObjects from the set
In code that roughly translates to this
// 1. Get the contents of the file
NSError *error = NULL;
NSString *textFromFile = [[NSString alloc] initWithContentsOfFile:pathToFile
encoding:NSUTF8StringEncoding
error:&error];
if (!textFromFile) {
// handle error
}
// 2. Enumerate all the characters
// (I'm enumerating composed characters to be able to support for example Chinese)
NSMutableSet *characters = [NSMutableSet set];
[textFromFile enumerateSubstringsInRange:NSMakeRange(0, textFromFile.length)
options:NSStringEnumerationByComposedCharacterSequences
usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
// 3. Add them to a mutable set
[characters addObject:substring];
}];
// 4. Get all the objects from the set (note that it's not sorted)
NSArray *allCharacters = [characters allObjects];

Answer 2

Here's an NSString category that will make an NSArray of all characters in a string:
- (NSArray*)charactersAsArray
{
NSMutableArray* array = [#[] mutableCopy];
for (int i = 0; i < self.length; i++) {
NSRange composedCharRange = [self rangeOfComposedCharacterSequenceAtIndex:i];
NSString* character = [self substringWithRange:composedCharRange];
if (character) {
[array addObject:character];
}
}
return array;
}
Or for unique characters you can use:
- (NSArray*)uniqueCharactersAsArray
{
NSMutableArray* array = [#[] mutableCopy];
for (int i = 0; i < self.length; i++) {
NSRange composedCharRange = [self rangeOfComposedCharacterSequenceAtIndex:i];
NSString* character = [self substringWithRange:composedCharRange];
if (character && ![array containsObject:character]) {
[array addObject:character];
}
}
return array;
}
You can use it like this...
NSString* myString = #"disdiefgdsaéYsué8d9ieo";
NSArray* allCharactersArray = [myString charactersAsArray];
NSArray* uniqueCharactersArray = [myString uniqueCharactersAsArray];