CODEWITHSUNDEEP
objective-ciosclass
Anders Lundsgard
Anders Lundsgard

Reputation: 797

Need a simple sample on how to store/load my custom class for iOS development

I have the following objective-c class:

@interface LatLongData {
    NSMutableString *_lat;
    NSMutableString *_long;
    NSMutableString *_altitude;
}

-(LatLongData*) initWithLat:(NSMutableString*) latitude Long:(NSMutableString*) longitude Altitude:(NSMutableString*) altitude;

@end

How can I store/load an instance of that object? I have tried working with code like this:

LatLongData *data = [[LatLongData alloc] initWithLat:_lat Long:_long Altitude:_altitude];

// Save
NSData *theData = [NSKeyedArchiver archivedDataWithRootObject:data];
[[NSUserDefaults standardUserDefaults] setObject:theData forKey:LatLongDataKey];

//...

// Load
NSData *loadedData = [[NSUserDefaults standardUserDefaults] dataForKey:LatLongDataKey];
LatLongData *ldata = (LatLongData *)[NSKeyedUnarchiver unarchiveObjectWithData:theData];

But I have no luck with that... I know I should read everything about Core Data. I will but at this point it would be very nice to get my little sample to work.

Upvotes: 1

Views: 128

Answers (1)

VenoMKO
VenoMKO

Reputation: 3294

You need to use NSCoding protocol with your class.
@interface LatLongData <NSCoding>

Here are a few protocol methods: 

- (id)initWithCoder:(NSCoder *)aDecoder
{
    if ((self = [super init])) {
        lat = [[aDecoder decodeObjectForKey:@"lat"] copy];
        long = [[aDecoder decodeObjectForKey:@"long"] copy];
        alt = [[aDecoder decodeObjectForKey:@"alt"] copy];
    }
    return self;
}

- (void)encodeWithCoder:(NSCoder *)aCoder
{
    [aCoder encodeObject:lat forKey:@"lat"];
    [aCoder encodeObject:long forKey:@"long"];
    [aCoder encodeObject:alt forKey:@"alt"];
}

P.S. You need to replace theData at your last line with loadedData

Upvotes: 3

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