Can't get NSData into NSMutableArray - objective-c

Question

I have an array of objects that I want to save as a file and reload back into my app. It's saving the file (with some data inside) but I can't get it to read back into a NSMutable Array.
The objects are models that conform to the NSCoding protocol:
#implementation myModel
#synthesize name;
#synthesize number;
-(void) encodeWithCoder: (NSCoder *) encoder
{
[encoder encodeObject:name forKey:#"name"];
[encoder encodeInteger:number forKey:#"number"];
}
-(id) initWithCoder: (NSCoder *) decoder
{
name = [decoder decodeObjectForKey:#"name"];
number = [decoder decodeIntegerForKey:#"number"];
return self;
}
#end
So I create an array of these objects, then I save it...
- (void) saveMyOptions {
// Figure out where we're going to save the app's data files
NSString *directoryPath = [NSString stringWithFormat:#"%#/Library/Application Support/MyAppDir/", NSHomeDirectory()]; // points to application data folder for user
// Figure out if that directory exists or not
BOOL isDir;
NSFileManager *fileManager = [[NSFileManager alloc] init];
[fileManager fileExistsAtPath:directoryPath isDirectory:&isDir];
// If the directory doesn't exist, create it
if (!isDir)
{
[fileManager createDirectoryAtPath:directoryPath withIntermediateDirectories:YES attributes:nil error:NULL];
}
// Assemble everything into an array of objects with options
NSMutableArray *savedPreferences = [[NSMutableArray alloc] init];
myModel *saveOptions = nil;
for (int i; i < [otherArray count]; i++)
{
saveOptions = [[myModel alloc] init];
[saveOptions setName:#"Some String"];
[saveOptions setNumber:i];
[savedPreferences addObject:saveOptions];
saveOptions = nil;
}
// Actually save those options into a file
NSData* saveData = [NSKeyedArchiver archivedDataWithRootObject:savedPreferences];
NSString *fileName = [NSString stringWithFormat:#"%#filename.stuff", directoryPath];
NSError *error = nil;
BOOL written = [saveData writeToFile:fileName options:0 error:&error];
if (!written)
{
NSLog(#"Error writing file: %#", [error localizedDescription]);
}
}
So now I try to load that data back into an array. This is where I think it's falling apart...
- (NSMutableArray *) loadOptions {
// Create file manager object
NSFileManager *fileManager = [[NSFileManager alloc] init];
NSData *saveData = nil;
// Find user directory path
NSString *directoryPath = [NSString stringWithFormat:#"%#/Library/Application Support/MyAppDir/", NSHomeDirectory()]; // points to application data folder for user
// Assign file name
NSString *fileName = [NSString stringWithFormat:#"%#filename.stuff", directoryPath];
// Create options array
NSMutableArray *myOptions = nil;
// If the file exists, fill the array with options
if ([fileManager fileExistsAtPath:fileName])
{
saveData = [NSData dataWithContentsOfFile:fileName];
myOptions = [NSKeyedUnarchiver unarchiveObjectWithData:saveData];
}
NSLog(#"%lu", [myOptions count]); // This ALWAYS reports 0!
NSLog(#"%lu", [saveData length]); // This reports a value of 236;
return myOptions;
}
Could someone point me in the direction of where I'm going wrong? I'm throughly confused :-(
Thanks in advance!

Answer 1

You are missing the super calls in your encodeWithCoder: and initWithCoder: methods, but that's just a guess. Why not use NSUserDefaults for saving preferences?
You might also want to make sure that your objects are retained is set using the synthesized setter.
- (void)encodeWithCoder:(NSCoder *)encoder {
[super encodeWithCoder:encoder];
[encoder encodeObject:name forKey:#"name"];
[encoder encodeInteger:number forKey:#"number"];
}
- (id)initWithCoder:(NSCoder *)decoder {
self = [super initWithCoder:decoder];
if (self) {
self.name = [decoder decodeObjectForKey:#"name"];
self.number = [decoder decodeIntegerForKey:#"number"];
}
return self;
}
For your info, NSKeyedArchiver also has a method you can use directly to operate on files:
+ (BOOL)archiveRootObject:(id)rootObject toFile:(NSString *)path
and NSKeyedUnarchiver:
+ (id)unarchiveObjectWithFile:(NSString *)path