Unable to save table data via NSCoding - ios

Question

I have an array of Objects (containing an item name and a creation date) used to display table data. I want to save this array using NSCoding protocol. I call my saveDataToDisk method every time a "submit" button is pressed to submit a new table entry. However, my app crashes upon hitting submit. This is my first time learning how to save app data and I looked a several tutorials and my form seems to be the same. I also looked for several days on the internet and couldn't find a solution. What is wrong?
Here are my methods:
Decoder Method:
- (id)initWithCoder:(NSCoder *)decoder {
self = [super initWithCoder:decoder];
if (!self) {
return nil;
}
self.itemArray = [decoder decodeObjectForKey:#"itemArray"];
return self;
}
Encoder Method:
- (void)encodeWithCoder:(NSCoder *)encoder {
[encoder encodeObject:self.itemArray forKey:#"itemArray"];
}
Path Finder Method:
- (NSString*) pathForDataFile
{
NSFileManager * fileManager = [NSFileManager defaultManager];
NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *filePath = [documentsPath stringByAppendingPathComponent:#"appData"];
if([fileManager fileExistsAtPath:filePath] == NO)
{
[fileManager createDirectoryAtPath:filePath withIntermediateDirectories:NO attributes:nil error:nil];
}
NSString *fileName = #"Budgetlist.appData";
return [filePath stringByAppendingPathComponent: fileName];
}
Save Data Method:
- (void) saveDataToDisk
{
NSString * path = [self pathForDataFile];
NSMutableDictionary * rootObject;
rootObject = [NSMutableDictionary dictionary];
[rootObject setValue: [self itemArray] forKey:#"itemArray"];
[NSKeyedArchiver archiveRootObject: rootObject toFile: path];
}
Load Data Method:
- (void) loadDataFromDisk
{
NSString * path = [self pathForDataFile];
NSDictionary * rootObject;
rootObject = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
[self setItemArray: [rootObject valueForKey:#"itemArray"]];
}
My Button:
- (IBAction)submitButton:(id)sender {
if (self.textField.text.length > 0 && [self.textField.text floatValue]>0) {
self.item = [[Data alloc] init];
self.item.itemName = self.textField.text;
[self.itemArray addObject:self.item];
[self.tableView reloadData];
[self saveDataToDisk];
}
}

Answer 1

You are trying to save an NSArray with custom objects.
Your objects must implement NSCoding protocol as well.
Implement those:
- (id)initWithCoder:(NSCoder *)decoder
- (void)encodeWithCoder:(NSCoder *)encoder
in your "Data" class.
NSArray is going through all objects and call those methods for each object inisde an array