Best way to save to nsuserdefaults for custom class?

Question

If I have a custom class Person which has three variables (which are propertized and synthesized):

NSString* theName;
float* theHeight;
int theAge;

Person instances are stored in an NSArray 'Group'. There is only one Group. What is the best way of storing and loading the Group in NSUserDefaults? (bearing in mind that float and int are not legal for NSUserDefaults)

Answer 1

Write yer class like this:

@interface Person: NSObject <NSCoding> {
  NSString *name;
  float *height;    //Note height is a pointer, presumabaly due to a dependancy in code we dont control
  NSUInteger age;
}

@property (nonatomic, retain) NSString *name;
@property (readwrite) height;
@property (readwrite) age;

@end

@implementation Person

@synthesize name;
@synthesize height;
@synthesize age;

#define PersonNameKey @"PersonNameKey"
#define PersonHeightKey @"PersonHeightKey"
#define PersonAgeKey @"PersonAgeKey"

- (id)initWithCoder:(NSCoder *)decoder {
    self = [super init];
    if(self) {
        self.name = [decoder decodeObjectForKey:PersonNameKey];
            //height is a pointer to we need to do this
            &self.height = [decoder decodeFloatForKey:PersonHeightKey];
        self.age = [decoder decodeIntForKey:PersonAgeKey];
    }
    return self;
}

- (void)encodeWithCoder:(NSCoder *)encoder {
    [encoder encodeObject:self.name forKey:PersonNameKey];
    //dereferance the pointer to persist the value
    [encoder encodeFloat:*self.height forKey:PersonHeightKey]
    [encoder encodeInt:self.age forKey:PersonAgeKey];
}

- (void)dealloc {
    self.name = nil;
    [super dealloc];
}
@end

Then you can do a:

Person = [Person alloc] init];
person.name = @"name";
person.age = 10;
person.height = 1.6;
[NSUserDefaults standardUSerDefaults] setObject:person forKey:@"SomeKey"];

Person *newPerson = [[NSUserDefaults standardUSerDefaults] objectForKey:@"SomeKey"];

If you wanted to persist a collection of the objects you are in luck because NSArray is NSCoding Compliant. All you need to do is:

NSArray *arrayOfPersons = [person1, person2, person3, nil];
[NSUSerDefaults standardUSerDefaults] setObject:arrayOfPersons forKey@"SomeKey"];

Note: Ususaly before posting on SO I dbl check my code in a complier, but I'm reinstalling today so there may be typos.