How to read & write to an NSArray to plist? - iphone

Question

I'm having several issues based around reading and writing an NSArray to and from a plist.
I have created a plist file in the 'Supporting Files' folder which I want to use to initialise the app data with upon the first load.
Here is what my plist looks like:
I then use this code to try load the plist into the app:
NSError *error;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
filePath = [documentsDirectory stringByAppendingPathComponent:kDataFile];
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:filePath])
{
NSString *bundle = [[NSBundle mainBundle] pathForResource:#"Data" ofType:#"plist"];
[fileManager copyItemAtPath:bundle toPath:filePath error:&error];
}
I then try to load the data from the plist file like so, however nothing seems to be displayed.
NSMutableDictionary *savedData = [[NSMutableDictionary alloc] initWithContentsOfFile:filePath];
NSMutableArray *myNSArray = [[savedData objectForKey:#"KEY_Level_1"] mutableCopy];
savedData = nil;
Sorry if this is a simple task, however I've been looking at lots of tutorials and trying to work out how to do this with no luck. I'm getting really frustrated now - I would have thought it should be a simple thing to do.
NOTE: My NSArray will contain a whole bunch of NSDictionaries.

Answer 1

You need to check the return value of copyItemAtPath:toPath:error: and at least log the error if the method returns false:
if (![fileManager copyItemAtPath:bundle toPath:filePath error:&error]) {
NSLog(#"error: copyItemAtPath:%# toPath:%# error:%#", bundle, filePath, error);
return;
}
-[NSDictionary initWithContentsOfFile:] has no way to report errors, so if it's failing, you cannot easily figure out why. Try reading the file into an NSData and using -[NSPropertyListSerialization propertyListWithData:options:format:error:] to parse it:
NSData *data = [NSData dataWithContentsOfFile:filePath options:0 error:&error];
if (!data) {
NSLog(#"error: could not read %#: %#", filePath, error);
return;
}
NSMutableDictionary *savedData = [NSPropertyListSerialization propertyListWithData:data options:NSPropertyListMutableContainers format:NULL error:&error];
if (!savedData) {
NSLog(#"error: could not parse %#: %#", filePath, error);
return;
}
NSMutableArray *myNSArray = [savedData objectForKey:#"KEY_Level_1"];
savedData = nil;
if (!myNSArray) {
NSLog(#"error: %#: object for KEY_Level_1 missing", filePath);
return;
}
If you do this, you'll be able to more easily see why your data is not being loaded.
UPDATE
On further inspection, it looks like the top-level dictionary in your plist contains the key "Root". The value for "Root" is a dictionary containing the key "KEY_Level_1". So you need to do this:
NSMutableArray *myNSArray = [[savedData objectForKey:#"Root"] objectForKey:#"KEY_Level_1"];