I'm creating a simple iOS application consisting of a few UITableViewControllers. The information displayed in the view controllers will come from a xml file (that I'll include in the project's Resources or direct from dropbox or iCloud). The xml file's contents will be based on user input .
A few notes:
The data is based on the user input means not static. Ideally the app will load the data into "Core Data" from xml file.
Each additional run of the app will just pull data from some Core Data source (that I'm not completely familiar w/ yet) instead of re-loading it from the textfile.
right now I am using XMLwriter to generate simple xml file
Please guide me
thank you
The best pattern here seems to be to use the XML file to "seed" your Core Data database. This only happens the first time. After that you will never again use your XML file but simply update and sync your core data store.
This is far better than generating XML. The problem with XML files (like property lists) is that you have to write the entire file for each little incremental change. If you sync to a store somewhere online, this can take much too much time to be practical.
Assuming you can get a foundation object from the XML file, simply iterate through the object and insert a Core Data one by one.
for (NSDictionary *dict in xmlArray) {
Entity *newObject = [NSEntityDescription
insertNewObjectForEntityForName:#"Entity"
inManagedObjectContext:self.managedObjectContext];
newObject.attribute1 = [dict objectForKey:#"attribute1"];
newObject.attribute2 = [dict objectForKey:#"attribute2"];
// etc...
}
[self.managedObjectContext save:nil];
Related
I have been working on an app where the user inputs data stored in core data everyday (two attributes an NSNumber and one as NSDate) and I wanted to improve that by allowing the user to import data from a external file such as csv or any other supported format through a button click. Any suggestions on how to proceed efficiently to do this?
Thank you.
Edit: Just adding a screenshot of the csv file as well as the output of the csv parser as NSArray. Basicly need to fetch the attribute separately and store them in core data on button click.
- The input file as csv:
- Sample csv parser output(NSarray):
I needed to achieve something similar recently.
A couple of members of my project team wanted to take our app prototype out to show potential clients, but wanted to show different data to each client. We solved this by allowing members of our project team to create their own test data before meeting with the client.
I achieved this by creating an example .csv file and distributing it to the other guys in the project team. They populate it with their own test data and use iTunes File Sharing to drop the .csv test data file on to the device.
On load, the app scans its Documents directory for a the test data file. If it exists, it parses the .csv file and persists to the database.
For the CSV parsing, I used Dave DeLong's CHCSVParser: https://github.com/davedelong/CHCSVParser
Plenty of help is available on setting up iTunes file sharing for your app. A quick Google finds this tutorial (http://www.raywenderlich.com/1948/how-integrate-itunes-file-sharing-with-your-ios-app) which should help you out, if you need it.
Edit- added help on storing data from .csv in Core Data
You stated in your original post that you store an NSNumber and NSDate. Taking that as a starting point, you might have a .csv file in the following form:
+----------------+--------------+
+ NSNumberColumn | NSDateColumn |
+----------------+--------------+
+ 1 | 2013-05-15 |
+ 2 | 2013-06-15 |
+ 3 | 2013-07-15 |
+----------------+--------------+
Assuming the output from the CSV parser is an NSArray of NSArrays, you could create the Core Data objects as follows:
I would create a couple of macros for the column numbers:
#define NSNumberColumn 0
#define NSDateColumn 1
Then iterate over the rows in the .csv file:
NSArray *rows = [NSArray arrayWithContentsOfCSVFile:pathToFile]; //CHCSVParser specific parsing method
for (NSArray *row in rows)
{
NSString *numberString = [parsedCsvRow objectAtIndex:NSNumberColumn];
NSString *dateString = [parsedCsvRow objectAtIndex:NSDateColumn];
NSNumber *number = // parse numberString to an NSNumber. Plenty of other posts on achieving this.
NSDate *date = // parse NSDate from dateString. Plenty of other posts on achieving this.
NSManagedObjectContext *context = [self managedObjectContext];
NSManagedObject *myCoreDataObject = [NSEntityDescription insertNewObjectForEntityForName:#"MyCoreDataObject" inManagedObjectContext:context];
[myCoreDataObject setValue:number forKey:#"NSNumberColumn"];
[myCoreDataObject setValue:date forKey:#"NSDateColumn"];
NSError *error;
if (![context save:&error]) {
NSLog(#"%#", [error localizedDescription]);
}
}
Note: Input validation and null checks have been ommited for brevity. I have also taken the liberty of making up your NSManagedObject property names, this will need updating. The above code should be separated in to a more suitable class structure.
I'm not at a Mac right now, so unfortunately I can't check if this works.
Hope that helps.
Try to use plist or json, they are already supported on iOS instead of CSV. CSV would require an third party parser. Using json or plist you will only need to loop throught the elemnts of the collections to create you persistent store. If you have just the CSV you can do a mid conversion using different free tools that you can find for free on the internet and later add to your bundle or publish to your site.
Here's what you do when you already have your CSV file parsed and data is ready to use in Objective-C.
Create a separate context for the import. You don't know how big the data can be, so you probably don't want to block one of your existing contexts while importing.
Iterate through the entries in the parsed data and insert new managed objects configured from each entry.
Every 200, 500, or 1000 entries (different for everybody, you'll need to test what's working best for you) save the context and, if needed, post a notification that a batch has been imported.
To keep the memory low, reset the context and forget all the objects that you created in this import context.
After the loop is finished, don't forget to save the last time.
Now how do you bring the data into another context, say, UI context?
This depends on the way you organized your Core Data stack. For example, import context can be configured as a child of the UI context. In this case, after each save to the import context the changes will be pushed to the UI context (and don't forget to save the UI context as well to push changes further).
But this is not the most efficient approach, because UI context, which is a context on the main thread, is involved in the import, and additional work is done on the UI thread that blocks it. I recommend creating the import context not as a child, but connected to the persistent store coordinator directly. To bring changes to the UI context in this case you either need to call mergeChangesFromContextDidSaveNotification: method after each save or you just refetch in the UI context after each save and in the end. The latter is easier on the UI context and particularly on NSFetchedResultsController, if you use it, because it doesn't need to replay changes to the updated objects one-by-one.
I'm developing an app that manages messages, and I want the app connects to the server, get messages and save them in the database(coredata). If the messages already exist, doesnt do anything and if they dont, add them to the database.
I'm thinking some ways to do it but I don't know exactly what to do. Any help? Thanks in advance
I would recommend using Restkit framework http://restkit.org
Reskit provides integration with Core Data.
Pros of using Restkit:
- Combines HTTP request/responses API, along with object mapping, offline/caching support with Core Data, all in one framework
- Object Mapping means that you're writing clean code, you define your classes and how they map to the JSON attributes, then you GET/POST/DELETE with few lines of code after that
- Core Data support means that your projects can work offline, data is sync when working online, but persistent when you need it offline
- The framework is well maintained
Cons:
- Works only with JSON REST APIs
- There can be a steep learning curve for some aspects
- Can be challenging if you work with REST APIs that are not completely 'standard'
The simplest way is to add a guid attribute (an identifier of type NSString, for example) to the entity you are interested in and check for that guid when you import data.
Here, you have two ways: let the server generate the guid for you or implement your own algorithm in the client side (iPhone, iPad, etc.). In both cases you need to be sure the guid is unique for each message.
So, for example, suppose the server generates the messages (and each message has its own guid). When you import data you also save the guid for each message object. If you have already a message with a specific guid, you don't add it, otherwise you add it. This could be done using the Find-or-Create pattern (see Implementing Find-or-Create Efficiently).
Hope that helps.
This is simple, it took me sometime to learn this, I use it in most of my apps.
First you need an ID of the fetched item, for example messageID.
When you fetch the JSON with all the items, for example using AFNetworking, you're going to receive an array of objects in NSDictionaries.
Before parsing the item load all the IDs of your stored items in a NSMutableDictionary (key => messageID, value objectID, this is related to the Core Data fault).
Don't forget to init the NSMutableArray somewhere:
_dictionaryOfEventIDAndObjectID = [NSMutableDictionary dictionary];
- (void)prepareDictionaryOfMessageIDs
{
[self.dictionaryOfEventIDAndObjectID removeAllObjects];
NSError *error = nil;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:#"Message"];
[fetchRequest setResultType:NSDictionaryResultType];
NSExpressionDescription *objectIDDescription = [[NSExpressionDescription alloc] init];
objectIDDescription.name = #"objectID";
objectIDDescription.expression = [NSExpression expressionForEvaluatedObject];
objectIDDescription.expressionResultType = NSObjectIDAttributeType;
[fetchRequest setPropertiesToFetch:#[objectIDDescription, #"messageID"]];
NSArray *objectsDict = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
for (NSDictionary *objectDict in objectsDict) {
[self.dictionaryOfMessageIDAndObjectID setObject:[objectDict valueForKeyPath:#"objectID"] forKey:[objectDict valueForKeyPath:#"messageID"]];
}
}
Then in the fetched data completion block just add something like this:
for (NSDictionary *objectDict in objectsDict) {
NSString *fetchedID = [objectDict objectForKey:#"id"];
if ([self.dictionaryOfMessageIDAndObjectID objectForKey:fetchedID]) {
continue;
}
[self parseMessageFromDictionary:objectDict];
}
I am making an Iphone drinking card game app.
All the card mean something different and i want the user to be able to press an info button and then show a new screen with information about the current card. How can i make a document to load text from instead of using a bunch og long strings?
Thanks
You could look into plist files - they can be loaded quite easily into the various collection objects and edited with the plist editor in Xcode.
For instance, if you organize your data as a dictionary, the convenience constructor
+ (id)dictionaryWithContentsOfURL:(NSURL *)aURL
from NSDictionary would provide you with as many easily accessible strings as you need.
This method is useful if you consider your strings primarily data as opposed to UI elements.
Update:
As #Alex Nichol suggested, here is how you can do it in practice:
To create a plist file:
In your Xcode project, for instance in the Supporting Files group, select New File > Resource > Property List
You can save the file in en.lproj, to aid in localization
In the Property list editing pane, select Add Row (or just hit return)
Enter a key name (for instance user1) and a value (for instance "Joe")
To read the contents:
NSURL *plistURL = [[NSBundle mainBundle] URLForResource:#"Property List" withExtension:#"plist"];
NSLog(#"URL: %#", plistURL);
NSDictionary *strings = [NSDictionary dictionaryWithContentsOfURL:plistURL];
NSString *user1 = [strings objectForKey:#"user1"];
NSLog(#"User 1: %#", user1);
A plist, a JSON string, and an SQLite database walked into a bar ...
Oops!! I mean those are the three most obvious alternatives. The JSON string is probably the easiest to create and "transport", though it's most practical to load the entire thing into an NSDictionary and/or NSArray, vs read from the file as each string is accessed.
The SQLite DB is the most general, and most speed/storage efficient for a very large number (thousands) of strings, but it takes some effort to set it up.
In my other answer, I suggest the use of a dictionary if your texts are mostly to be considered as data. However, if your strings are UI elements (alert texts, window titles, etc.) you might want to look into strings files and NSBundle's support for them.
Strings files are ideally suited for localization, the format is explained here.
To read them into you app, use something like this:
NSString *text1 = NSLocalizedStringFromTable(#"TEXT1", #"myStringsFile", #"Comment");
If you call your file Localizable.strings, you can even use a simpler form:
NSString *str1 = NSLocalizedString(#"String1", #"Comment on String1");
A useful discussion here - a bit old, but still useful.
Currently, I have an application where a user clicks on a map and adds annotation points with certain subtitles. However, when the phone is power-cycled, all their added points are gone. I'm interested in making these annotations persistent. I've been trying to figure out how to do this with Core-Data, but after reading this tutorial here: http://www.raywenderlich.com/934/core-data-tutorial-getting-started, I'm a bit lost on where to start.
Any help would be appreciated, thanks.
If you have a core data application set up, you will only need to create an entity in the xcdatamodel file. Add attributes for whatever you may want to store.
latitude - double
longitude - double
title - NSString
etc. until you have what you want.
When you want to add an annotation, you should create a new core data object for your entity. It will look something like this
Location *newLocation = (Location *)[NSEntityDescription insertNewObjectForEntityForName:#"Location" inManagedObjectContext:self.managedObjectContext];
Location.latitude = ....
// and so on to store the information you want in its attributes;
You can set the attributes at different point if you change the values at a later point. You just need to be able to access the right object to go with the annotation. You should be able to do this by using NSFetchRequest in your managedObjectContext. You can use NSPredicate to filter the objects to the one you want. Then when you are ready to exit the app, save your context using
NSError *error = nil;
if ([managedObjectContext save:&error]) {
// handle the error;
}
which will store all the objects you've added to be used next time you open the app. You will then be able to create your annotations based on the objects in your managedObjectContext. I hope this is what you were looking for, or at least gives you an idea how to approach what you'd like to do.
I'm trying to create a user editable plist where the user can store a custom created workout routine including strings referenced from another data.plist in the app bundle.
I'm assuming NSCoding is the best way to go about this. So far I have the interface setup as a nav bar and table view.
I want it to be blank be default and the user has to press the "+" that is in the top right of the nav bar. Then he could enter a name for an entry in an array, for example chest day, or bicep day. And within that array, will be a dictionary or another array of strings of the particular exercises for that day, for example bench press, or bicep curl.
This plist needs to be editable so it will be going in the users document folder and not in the app bundle.
Example:
Top array consists of Chest Day, Back Day, Leg Day. Within Chest Day dictionary, include bench press, chest pull, pushup, etc.
Update:
Adding this method to search for routine file;
-(void)loadData
{
if(YES)
{
NSString* documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString* routineFile = [documentsPath stringByAppendingPathComponent:#"routine.plist"];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:routineFile];
}
else
{
//load file
}
}
NSCoding is the protocol used by NSArchiver, NSKeyedArchiver, etc., not for serializing an array into a property list.
Forget about the idea that the user is going to edit a property list. The user is going to edit data in your app -- the fact that it's stored as a property list is just an implementation detail. When your app starts, you read the data stored in the data file. The user edits it, looks at it, whatever. At some point later, perhaps after each edit, perhaps just before the app quits, you write the data back out to the file. Since it's a property list, don't worry about updating the file; you already have all the data, so write a whole new property list and then use that file to replace the old one.
Perhaps I'm wrong and you really do intend for the user to edit the property list by hand, with a text editor. This would be a mistake. It's great the property lists are human readable, but asking your users to edit your raw data files by hand is a strong indication that your app is broken. The whole purpose of your app is to keep track of this information for the user; if they wanted to use a text editor to manage it, they wouldn't need your app. So, with that said, I hope I'm not wrong. ;-)
I don't think I'd use NSCoding for this - if all you're working with is standard plist objects like NSArray, NSDictionary, and NSString, the top array's -writeToFile:atomically: method is an easy way to do the job.