如何在NSUserDefaults中保存NSMutablearray

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!

Answer 3

I want just to add to the other answers that the object that you are going to store store in the NSUserDefault , as reported in the Apple documentation must be conform to this:

"The value parameter can be only property list objects: NSData , NSString , NSNumber , NSDate, NSArray, or NSDictionary. For NSArray and NSDictionary objects, their contents must be property list objects."

here the link to property list programming guide

so pay attention about what is inside your array

Answer 4

Save:

NSUserDefaults.standardUserDefaults().setObject(PickedArray, forKey: "myArray")
 NSUserDefaults.standardUserDefaults().synchronize()

Retrieve:

if let PickedArray = NSUserDefaults.standardUserDefaults().stringForKey("myArray") {
    print("SUCCCESS:")
    println(PickedArray)
}

Answer 5

Do you really want to store images in property list? You can save images into files and store filename as value in NSDictionary .

define path for store files

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
self.basePath = [paths firstObject];

Store and load image:

- (NSString *)imageWithKey:(NSString)key {
    NSString *fileName = [NSString stringWithFormat:@"%@.png", key]
    return [self.basePath stringByAppendingPathComponent:fileName];
}

- (void)saveImage:(UIImage *)image withKey:(NSString)key {
    NSData *imageData = UIImagePNGRepresentation(image);
    [imageData writeToFile:[self imageWithKey:key] atomically:YES];
}

- (UIImage *)loadImageWithKey:(NSString)key { {
    return [UIImage imageWithContentsOfFile:[self imageWithKey:key]];
}

And you can store path or indexes in NSMutableDictionary

- (void)saveDictionary:(NSDictionary *)dictionary {
    NSMutableDictionary *dictForSave = [@{ } mutableCopy];
    for (NSString *key in [dictionary allKeys]) {
        [self saveImageWithKey:key];
        dictForSave[key] = @{ @"image" : key };
    }
    [[NSUserDefaults standardUserDefaults] setObject:dictForSave forKey:@"MyDict"];
}

- (NSMutableDictionary *)loadDictionary:(NSDictionary *)dictionary {
    NSDictionary *loadedDict = [[NSUserDefaults standardUserDefaults] objectForKey:@"MyDict"];
    NSMutableDictionary *result = [@{ } mutableCopy];
    for (NSString *key in [loadedDict allKeys]) {
        result[key] = [self imageWithKey:key];
    }
    return result;
}

In NSUserDefaults you can store only simply objects like NSString , NSDictionary , NSNumber , NSArray .

Also you can serialize objects with NSKeyedArchiver/NSKeyedUnarchiver that conforms to NSCoding protocol .

Answer 6

如果你需要以特定的顺序将字符串添加到NSMutableArray ，或者如果你使用NSMutableArray作为UITableView你可能想要使用它：

[NSMutableArray insertObject:string atIndex:0];

Answer 7

In Swift 3, for an NSMutableArray, you will need to encode/decode your array to be able to save it/ retrieve it in NSUserDefaults :

Saving

//Encoding array
let encodedArray : NSData = NSKeyedArchiver.archivedData(withRootObject: myMutableArray) as NSData

//Saving
let defaults = UserDefaults.standard
defaults.setValue(encodedArray, forKey:"myKey")
defaults.synchronize()

Retrieving

//Getting user defaults
let defaults = UserDefaults.standard

//Checking if the data exists
if defaults.data(forKey: "myKey") != nil {
   //Getting Encoded Array
   let encodedArray = defaults.data(forKey: "myKey")

   //Decoding the Array
   let decodedArray = NSKeyedUnarchiver.unarchiveObject(with: encodedArray!) as! [String]
}

Removing

//Getting user defaults
let defaults = UserDefaults.standard

//Checking if the data exists
if defaults.data(forKey: "myKey") != nil {

    //Removing the Data
    defaults.removeObject(forKey: "myKey")

}

Answer 8

Save information of Array in NSUserdefaults with key.

"MutableArray received from JSON response"

[[NSUserDefaults standardUserDefaults] setObject:statuses forKey:@"arrayListing"];

"Retrieve this information(Array) anywhere in the project with same key"

NSArray *arrayList = [[NSUserDefaults standardUserDefaults] valueForKey:@"arrayListing"];

This helped me in my project and hope, it will help someone.

Answer 9

Swift Version:

Save Array in NSUserDefaults:

NSUserDefaults.standardUserDefaults().setObject(selection, forKey: "genderFiltersSelection")

Retrieve Bool Array From NSUserDefaults:

if NSUserDefaults.standardUserDefaults().objectForKey("genderFiltersSelection") != nil{
                selection = NSUserDefaults.standardUserDefaults().objectForKey("genderFiltersSelection") as? [Bool] ?? [Bool]()
   }

Retrieve String Array From NSUserDefaults:

if NSUserDefaults.standardUserDefaults().objectForKey("genderFiltersSelection") != nil{
                selection = NSUserDefaults.standardUserDefaults().objectForKey("genderFiltersSelection") as? [String] ?? [String]()
    }