NSMutableArray in NSUserDefaults - iphone

Question

I'm sorry for my bad english but i'm trying to explain with best words.
I have some problem when i'm trying to insert an NSMutableArray in NSUserDefaults ([NSUserDefaults setObject:forKey:]: Attempt to insert non-property value ')
My code to insert the array is as follows:
-(void)saveToUserDefaults:(NSMutableArray*)myArray
{
NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
NSArray *array = [[NSArray alloc ] initWithArray:myArray];
if (standardUserDefaults)
{
[standardUserDefaults setObject:array forKey:#"MyArray"];
[standardUserDefaults synchronize];
}
}
My code to retrieve the array:
-(NSMutableArray*)retrieveFromUserDefaults
{
NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
NSMutableArray *val = [[NSMutableArray alloc]init];
if (standardUserDefaults)
val = [NSMutableArray arrayWithArray:[standardUserDefaults arrayForKey:#"MyArray"]];
return val;
}
and in my code :
NSMutableArray :
series = [[NSMutableArray alloc]initWithObjects:nil];
//add some object inf my array...
Save my NSMutableArray :
[self saveToUserDefaults:series];
Retrieve my NSMutableArray :
series = [self retrieveFromUserDefaults];
I think it's not the best way to do this, so if anyone have ideas , it'll be helpful for me.
Thanks for reading.
Tommy

Answer 1

Only immutable NSArrays can be placed into defaults. Rather than placing a NSMutableArray there, convert to regular array using [NSArray arrayWithArray:] and place that one into defaults.
For retrieval, retrieve an NSArray and then use [NSMutableArray arrayWithArray:].

Answer 2

You can use following method to get the mutable object from immutable. It's not optimized and only implemented for NSArray and NSDictionary.
+ (id) GetMutable:(id)input {
id result;
if ([input superclass] == [NSArray class] || [input superclass] == [NSMutableArray class]) {
result = [[NSMutableArray alloc] initWithArray:input copyItems:YES];
for (int i = 0; i < [(NSMutableArray*)result count]; i++) {
[(NSMutableArray*)result replaceObjectAtIndex:i withObject:[Globals GetMutable:[(NSMutableArray*)result objectAtIndex:i]]];
}
} else if ([input superclass] == [NSDictionary class] || [input superclass] == [NSMutableDictionary class]) {
result = [[NSMutableDictionary alloc] initWithDictionary:input copyItems:YES];
NSArray *keys=[(NSMutableDictionary*)result allKeys];
for (int i = 0; i < keys.count; i++) {
[(NSMutableDictionary*)result setObject:[Globals GetMutable:[(NSMutableDictionary*)result objectForKey:[keys objectAtIndex:i]]] forKey:[keys objectAtIndex:i]];
}
}
else {
return input;
}
return result;
}

Answer 3

I hope this tutorial helps, who expect answer for this question.
-(void)saveToUserDefaults:(NSString*)myServerName uname:(NSString*)myUserName
pass:(NSString*)myPassword
{
NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
if (standardUserDefaults) {
[standardUserDefaults setObject:myServerName forKey:#"ServerKey"];
[standardUserDefaults setObject:myUserName forKey:#"UserNameKey"];
[standardUserDefaults setObject:myPassword forKey:#"PasswordKey"];
[standardUserDefaults synchronize];
}
}
-(NSArray*)retrieveFromUserDefaults
{
NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
NSString *serverName = nil;
NSString *userName = nil;
NSString *password = nil;
if (standardUserDefaults)
serverName = [standardUserDefaults objectForKey:#"ServerKey"];
userName = [standardUserDefaults objectForKey:#"UserNameKey"];
password = [standardUserDefaults objectForKey:#"PasswordKey"];
NSArray* credentials = [NSArray arrayWithObjects:serverName,userName,password, nil];
return credentials;
}
To Pass values
[self saveToUserDefaults:serverVariable uname:usernameVariable pass:passVariable];
To get Values
NSArray *result=[self retrieveFromUserDefaults];
Happy coding!!!

Answer 4

The contents of your array can only by plist valid objects: (NSString, NSNumber, NSDate, NSData, NSArray, or NSDictionary objects).
See documentation for NSUserDefaults setObject:forKey: and What is a Property List?

Answer 5

Your code needs a lot of clean up. Here is the simple and correct way to access standard user defaults:
The value you pass to your save method does not need to be mutable, although it can be. But since you are not mutating it inside your method, there's no need for it to be mutable. It just has to be not nil, which you'll check before saving:
-(void)saveToUserDefaults:(NSArray*)myArray
{
if (myArray) {
NSUserDefaults *myDefaults = [NSUserDefaults standardUserDefaults];
myDefaults[#"myArray"] = myArray;
}
}
Standard user defaults only returns non-mutable objects, which you can convert to a mutable copy using the "mutableCopy" method:
-(NSMutableArray*)retrieveFromUserDefaults
{
NSUserDefaults *myDefaults = [NSUserDefaults standardUserDefaults];
NSMutableArray *val = [[NSMutableArray alloc] init];
val = [myDefaults[#"MyArray"] mutableCopy];
return val;
}