Load data from NSArray to NSManagedObject - ios

Question

is it possible to load data from .plist to core data object?
I have this code:
NSURL *url = [[NSBundle mainBundle] URLForResource:#"List" withExtension:#"plist"];
NSDictionary *plistContent = [NSDictionary dictionaryWithContentsOfURL:url];
NSArray *name = [plistContent objectForKey:#"Name"];
NSArray *surname = [plistContent objectForKey:#"Surname"];
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
for (NSString *aName in name) {
for (int i = 0; i < name.count; i++) {
[newManagedObject setValue:nameSt forKey:#"name"];
}
}
for (NSString *aSurname in content) {
for (int i = 0; i < content.count; i++) {
[newManagedObject setValue:contentSt forKey:#"surname"];
}
}
[self saveContext];
I have 3 strings with name and 3 string with surname, but in
newManagedObject load only 1 string from each array. Please help me to solve this problem

Answer 1

You create only one object, but you should create 3 (inside the loop). You should also only have 1 loop (not the 4 that you currently have...):
NSURL *url = [[NSBundle mainBundle] URLForResource:#"List" withExtension:#"plist"];
NSDictionary *plistContent = [NSDictionary dictionaryWithContentsOfURL:url];
NSArray *names = [plistContent objectForKey:#"Name"];
NSArray *surnames = [plistContent objectForKey:#"Surname"];
if (names.count == surnames.count) {
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
for (int i = 0; i < names.count; i++) {
NSString *name = names[i];
NSString *surname = surnames[i];
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
[newManagedObject setValue:name forKey:#"name"];
[newManagedObject setValue:surname forKey:#"surname"];
}
[self saveContext];
} else {
// error...
}

Answer 2

I don't think it's a good practice to store arrays of names and surnames in plist moreover separately... Anyway if this is really necessary, better to store array of persons with struct like your model
persons : [
{ name: Angelina,
surname: Jolie
},
{ name: Steven,
surname: Jobs
}
]
Then it will be easy to use method setValuesForKeysWithDictionary without unnecessary loops. If you are interesting, I can to show a more detailed example
EDIT: so if you have a lot of properties in you model, you can use setValuesForKeysWithDictionary method just once instead of setValue:forKey: for each key, but you need to overwrite last method in your model using mapping like this:
+ (NSDictionary *)mappings {
static NSDictionary *singleton = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
singleton = #{#"Name" : #"name",
#"Surname" : #"surname",
#"some_another_key" : #"your_property_name"};
});
return singleton;
}
- (void)setValue:(id)value forKey:(NSString *)key {
key = [[ModelClass mappings] objectForKey:key] ?: key;
if ([key isEqualToString:#"some_uniq_property"]) {
// ... do anything with value to transform it
// for example to get NSDate from NSString
}
[super setValue:value forKey:key];
}
- (void)setValue:(id)value forUndefinedKey:(NSString *)key {
// required method to avoid exception!
// you can intercept some key that you have forgotten to describe in mappings
// you can just retain it empty
NSLog(#"UndefinedKey: %#!!!", key);
}
Finally, your code will look something like this:
NSURL *url = [[NSBundle mainBundle] URLForResource:#"List" withExtension:#"plist"];
NSDictionary *plistContent = [NSDictionary dictionaryWithContentsOfURL:url];
NSArray *persons = [plistContent objectForKey:#"Persons"];
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
for (NSDictionary *person in persons) {
ModelClass *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
[newManagedObject setValuesForKeysWithDictionary:person];
}
[self saveContext];
For example: if you will want to rename some key or add new property to your model, you just will need to change mapping method instead going around all project and searching every place created\updated your managed objects