Objective-C NSData initWithContentsOfFile, check if file exists?

Should I check if a file exists at a given path when trying to read the data into an NSData object? Right now I'm not doing at the moment but my code works since my array that is supposed to get populated with data from the file will be set to nil and I can later in my application check if that array is nil. But I'm thinking that the code is perhaps "ugly" and would work better if i did a check (like the one in the commented code).

NSData *codedData = [[NSData alloc] initWithContentsOfFile:[CareersParser dataFilePath]];

    /*
    if (codedData != nil) {
        //do the below (not commented out code)
    } else {

        //file doesn't exist at the given path
        [codedData release];
        return nil;
    }
    */

    NSKeyedUnarchiver *unarchive开发者_运维百科r = [[NSKeyedUnarchiver alloc] initForReadingWithData:codedData];
    NSArray *careers = [unarchiver decodeObjectForKey:kDataKey];    
    [unarchiver finishDecoding];

    NSMutableArray *ids = [[NSMutableArray alloc] init];

    for (Career *career in careers) {
        [ids addObject:[career id]];
    }

    // Sort the array in an orderly fashion
    NSArray *sortedIds = [ids sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];

    // Release allocated memory
    [ids release];
    [unarchiver release];
    [codedData release];

    return sortedIds;

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That seems sensible to me I would reverse the if statement to do away with the else clause.

if (nil == codedDate) {
  [codedData release];
  return nil;
}

... Do the rest of your code

Apple suggests here that you should attempt to perform an operation such as loading data like you have suggested. As long as you don't try to do [[NSManager defaultManager] fileExistsAtPath:path] you won't be introducing race conditions.

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You don't, and this could introduce a race, so it will be more "ugly". Just check if codedData if nil in case of reading failure.