iCloud Document Storage with UIDocument - Beginning iOS Cloud and Database Development - page 77

include a file type version with your UIDocuments so that down the line you have flexibility if you need
to change your document model in future releases.
The next thing we do is convert our thumbnail data into an NSData object using
UIImagePNGRepresentation() . Next we call encodeObject:forKey: twice on our NSCoder object. The
first one is for our thumbnail data and the second is for our display name string.
Moving on to the initWithCoder: method, we also receive an NSCoder object as the parameter.
Because this is our read method, we start out by calling the decodeIntForKey: method on our
NSCoder with the key kVersionKey . Now that we have extracted the version number, we check to
see if it is equal to 1. If it isn't, we just return a blank initialized CTMetadata object. If it is, we use the
decodeObjectForKey : method to get our Image data and our display name. The image data then has
to be converted to a UIImage object using the imageWithData: class method on UIImage . Finally we
return our fully initialized CTMetadata object by calling initWithThumbnail:andDisplayName: .
That is all there is to our CTMetadata object. Now we need to create our actual data model. Let's
create another new Objective-C class that is a subclass of NSObject and call it CTData . Just like we
did with CTMetadata we want to subscribe to the NSCoding protocol. Then we will add some public
properties.
@property (strong) NSString *firstName;
@property (strong) NSString *lastName;
@property (strong) NSString *displayName;
@property (strong) NSNumber *favoriteNumber;
@property (strong) UIImage *photo;
Now we can move on over to the CTData.m file. We will be doing the exact same thing that we did in
the CTMetadata.m file. Here is what your .m file should look like when you are done:
#import "CTData.h"
#define kVersionKey @"VERSION"
#define kFirstNameKey @"FIRST_NAME"
#define kLastNameKey @"LAST_NAME"
#define kDisplayNameKey @"DISPLAY_NAME"
#define kFavoriteNumberKey @"FAVORITE_NUMBER"
#define kPhotoKey @"PHOTO"
@implementation CTData
- (id)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName displayName:(NSString *)
displayName favoriteNumber:(NSNumber *)favoriteNumber andPhoto:(UIImage *)photo {
if((self = [super init])){
_firstName = firstName;
_lastName = lastName;
_displayName = displayName;
_favoriteNumber = favoriteNumber;
_photo = photo;
}
return self;
}