Question

I am new to iOS development and could not find a way to solve this problem:

I have an app that has two views: one where the user enters some information (say a string), and another view where there is a tableview that includes all the strings that were ever entered (like a history view).

What I am trying to find is a good way to store the input string, then load it into the table view data source once the user switches to the history. I tried to use NSUserdefault but with not much success. Just getting messed up with the data structures, etc.

Here is what I am doing on the main view (where the user enters the input string):

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];     
    NSMutableArray *arr1 = [[NSMutableArray alloc] init];
    arr1 = [defaults arrayForKey:@"historyNames"];

    [arr1 addObject:string];

    [defaults setObject:arr1 forKey:@"historyNames"];    

From some reason I get a warning where I read to arr1, and honestly, I doubt that should work anyway.

Can anyone suggest how I could modify this to work properly and achieve what I am looking for?

Thanks.

Answer 1

[defaults arrayForKey:@"historyNames"];

Will return nil if you never initialized and saved an array for that key in NSUSerDefaults.

If you initialize and array and set it once (look up how to initialize default values for NSUserDefaults), it will return a proper array.

Then you can just do

NSMutableArray *arr1  = [NSMutableArray arrayWithArray:[[defaults arrayForKey@"historyNames"]];

Depending on how many elements this array will have, you may be better off using Core Data. Using user defaults is not very efficient for many/large values, just for small settings and things like that.