How to save custom objects in array and store it i

问题:

I am getting my custom class object after button action method. Now I need to store multiple custom objects in NSMutableArray and then store this array in NSUserDefaults.

Here is my code :

-(IBAction)onClickSubmitLater:(id)sender
{
    //Saving store in user defaults for later upload data.

    NSMutableArray *arrayStoreList = [[NSMutableArray alloc] init];
    arrayStoreList = [Util getArrayPreference:@"Store"];//arrayStoreList is the list of all stores.

    Store *store = [[Store alloc] init];
    store = [arrayStoreList objectAtIndex:self.selectedStoreIndex];//here i am getting particular store that i need to save in array.

    //archive
    NSData *dataStore = [NSKeyedArchiver archivedDataWithRootObject:store];
    [[NSUserDefaults standardUserDefaults] setObject:dataStore forKey:@"resultStore"];

    //unarchive
    NSData *dataResultStore = [[NSUserDefaults standardUserDefaults] objectForKey:@"resultStore"];

    Store *resultStore = (Store *)[NSKeyedUnarchiver unarchiveObjectWithData:dataResultStore];
    NSLog(@"%@", resultStore);
}

Using above code, it is saving single Custom class Store object in NSUserDefaults. So I would like to save all Store object in NSMutableArray after submit later ibaction. Later, I will fetch array of stores for uploading store on server one by one.

Thanks.

回答1:

To store and retrieve array with custom object on user defaults you can use following methods:

-(void)writeArrayWithCustomObjToUserDefaults:(NSString *)keyName withArray:(NSMutableArray *)myArray
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:myArray];
    [defaults setObject:data forKey:keyName];
    [defaults synchronize];
}

-(NSArray *)readArrayWithCustomObjFromUserDefaults:(NSString*)keyName
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSData *data = [defaults objectForKey:keyName];
    NSArray *myArray = [NSKeyedUnarchiver unarchiveObjectWithData:data];
    [defaults synchronize];
    return myArray; 
}

But make sure you have implemented

- (void) encodeWithCoder : (NSCoder *)encode ;
- (id) initWithCoder : (NSCoder *)decode;

method in data model class to avoid crash as followings:

- (void)encodeWithCoder:(NSCoder *)coder;
{
    [coder encodeObject:label forKey:@"label"];
    [coder encodeInteger:numberID forKey:@"numberID"];
}

- (id)initWithCoder:(NSCoder *)coder;
{
    self = [super init];
    if (self != nil)
    {
        label = [[coder decodeObjectForKey:@"label"] retain];
        numberID = [[coder decodeIntegerForKey:@"numberID"] retain];
    }   
    return self;
}

回答2:

You need to archive it by implementing NSCoding protocol. Then you can write it to any file.

Implement these methods in your model :

- (void) encodeWithCoder : (NSCoder *)encode ;
- (id) initWithCoder : (NSCoder *)decode;

As you say, you have implemented this in the Class, now you need to save the array.

For saving and reading the array, you need to use :;

[[NSUserDefaults standardUserDefaults] setObject:yourMutableArray forKey:@"keyForArray"];
NSMutableArray *array = [NSMutableArray arrayWithArray:[[NSUserDefaults standardUserDefaults] objectForKey:@"keyForArray"]];

回答3:

This two methods will mainly used to store and retrieve custom object's property.

- (void)encodeWithCoder:(NSCoder *)encoder ;
- (id)initWithCoder:(NSCoder *)decoder;

Take look at @chrissr's answer, @Brad Larson's answer