Writing new keys to a .plist file based on textField - ios

Question

What I want to do is to populate a pickerView from an array based on a .plist, which can be added to from a textField. I've got it to work, but it only adds one key and replaces it when a new one is added. For instance if I add "hello", and then try to add another one, it replaces hello with something else.
- (IBAction)setContext:(id)sender {
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString *path = [[NSBundle mainBundle] pathForResource:#"fullArray" ofType:#"plist"];
NSString *textFieldText = textField.text;
NSMutableDictionary *rootDict = [[NSMutableDictionary alloc] initWithContentsOfFile:path];
[rootDict setValue:textField.text forKey:textField.text];
NSString *writablePath = [documentsDirectory stringByAppendingPathComponent:#"fullArray.plist"];
[rootDict writeToFile:writablePath atomically: YES];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); //1
NSString *plistPath = [documentsDirectory stringByAppendingPathComponent:#"fullArray.plist"]; //3
NSDictionary *dictionary = [[NSDictionary alloc] initWithContentsOfFile:plistPath];
NSArray *array = [dictionary allKeys];
arrayContext = [[NSMutableArray alloc] initWithArray:array];
[pickerView selectRow:0 inComponent:0 animated:YES];
[textField endEditing:YES];
[pickerView reloadAllComponents];
}
How can I fix this?

Answer 1

Ok, you are creating a new NSMutableDictionary every time you pick something in the picker, the correct approach is:
Create a NSMutableDictionary as a property.
Every time you pick, create a new string for the key, maybe using [NSString stringWithFormat:].
use [mutableDictionary setObject:forKey] for set a new object in the mutant dictionary, with the new created key.