[WP/160] How to store custom class using CoreData

0.h

@interface DBMetadata : NSObject <NSCoding> {
    BOOL thumbnailExists;
    long long totalBytes;
    NSDate *lastModifiedDate;
    NSString *path;

    // ...
}

1.m

- (id)initWithCoder:(NSCoder *)coder {
    if ((self = [super init])) {
        thumbnailExists = [coder decodeBoolForKey:@"thumbnailExists"];
        totalBytes = [coder decodeInt64ForKey:@"totalBytes"];
        lastModifiedDate = [coder decodeObjectForKey:@"lastModifiedDate"];
        path = [[coder decodeObjectForKey:@"path"] retain];

        // ...
    }
    
    return self;
}

- (void)encodeWithCoder:(NSCoder *)coder {
    [coder encodeBool:thumbnailExists forKey:@"thumbnailExists"];
    [coder encodeInt64:totalBytes forKey:@"totalBytes"];
    [coder encodeObject:lastModifiedDate forKey:@"lastModifiedDate"];
    [coder encodeObject:path forKey:@"path"];

    // ...
}