IPhone : Reading and Writing NSMutableArray to iPhone not working (Works on iOS Simulator)

In an app I am working on I want to have an NSMutableArray (called pathsArray) that I can read from a file in the app's directory, be able create an instance of that array that I can add objects to and/or remove objects from, and then I want to write it back to the file. I have a UILabel that shows the number of contents in this array. My problem: my code below works fine on Xcode's iOS Simulator but when I try to run the app on my actual iPhone the data isn't saved. I know there are a lot of questions on here related to this issue but i can't seem to see what I am doing wrong. Any help would be greatly appreciated.

- (void) loadArrayContents {
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* documentsDirectory = [paths objectAtIndex:0];
NSString* filePath = [documentsDirectory stringByAppendingString:@"theArray"];

//Objects contained in an array returned by 'initWithContentsOfFile' are immutable even if the array is mutable
NSArray* contentsArray = [[NSMutableArray alloc] initWithContentsOfFile:filePath];
pathsArray = [[NSMutableArray alloc] initWithArray:contentsArray];
}

and...

- (void) saveArrayContents {
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* documentsDirectory = [paths objectAtIndex:0];
NSString* filePath = [documentsDirectory stringByAppendingString:@"theArray"];

[pathsArray writeToFile:filePath atomically:YES]);
}