How to save NSMutablearray in NSUserDefaults

Question

I have two NSMutableArray's. They consist of images or text. The arrays are displayed via a UITableView. When I kill the app the data within the UITableView gets lost. How to save array in UITableView by using NSUserDefault?

Answer 1

Note: NSUserDefaults will always return an immutable version of the object you pass in.

To store the information:

// Get the standardUserDefaults object, store your UITableView data array against a key, synchronize the defaults NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults]; [userDefaults setObject:arrayOfImage forKey:@"tableViewDataImage"]; [userDefaults setObject:arrayOfText forKey:@"tableViewDataText"]; [userDefaults synchronize]; 

To retrieve the information:

NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults]; NSArray *arrayOfImages = [userDefaults objectForKey:@"tableViewDataImage"]; NSArray *arrayOfText = [userDefaults objectForKey:@"tableViewDataText"]; // Use 'yourArray' to repopulate your UITableView 

On first load, check whether the result that comes back from NSUserDefaults is nil, if it is, you need to create your data, otherwise load the data from NSUserDefaults and your UITableView will maintain state.

Update

In Swift-3, the following approach can be used:

let userDefaults = UserDefaults.standard  userDefaults.set(arrayOfImage, forKey:"tableViewDataImage") userDefaults.set(arrayOfText, forKey:"tableViewDataText") userDefaults.synchronize()  var arrayOfImages = userDefaults.object(forKey: "tableViewDataImage") var arrayOfText = userDefaults.object(forKey: "tableViewDataText") 

Answer 2

You can save your mutable array like this:

[[NSUserDefaults standardUserDefaults] setObject:yourArray forKey:@"YourKey"]; [[NSUserDefaults standardUserDefaults] synchronize]; 

Later you get the mutable array back from user defaults. It is important that you get the mutable copy if you want to edit the array later.

NSMutableArray *yourArray = [[[NSUserDefaults standardUserDefaults] arrayForKey:@"YourKey"] mutableCopy]; 

Then you simply set the UITableview data from your mutable array via the UITableView delegate

Hope this helps!