What's the best method for editing and saving a JSON file on the iPhone/iPod? I know there are libraries that allow you to easily read JSON data, but are there any that allow you to generate it?
TouchJSON reads and generates JSON, is quite fast, and uses very little memory.
JSON Framework is supposedly faster, but uses much more memory.
The iPhone also includes a built-in JSON parser/generator, but it's only available through private APIs. You probably shouldn't use this one.
TouchJSON allows conversion both to and from JSON with a single call like:
[[CJSONSerializer serializer] serializeObject:someDictionaryofYours];
Related
Can any body tell me which parser is best in my condition? XML, JSON or any else ?
The app contains feature link sync the data, communicate with the web-service and etc. So I am targeting parser which is light weight and fast.
I have lots of data which are parsed between iPhone and server.
Which are the option? Or any good link for comparison between different parser ?
I would suggest JSON as in terms of data size json tends to be compact compared to XML. Which will reduce time spent in network transfer (for your data).
You could use any available JSON parsers to directly get ObjectiveC objects. Some Json parsers -
NSJSONSerialization
json framework
jsonKit
I personally prefer jsonKit as its supposed to be fastest of all.
Of course it's JSON.
This is the frequent question asked on stack.You could find much better answer just by Goggling.
JSON has several advantages over XML. Its a lot smaller and less bloated, so you will be passing much less data over the network - which in the case of a mobile device will make a considerable difference.
Refer to JSON Tutorial for iPhone.
Mr.Devang. I recommend NSXMLParser. If your data or response from service will be in XML format please use NSXMLParser. Apple have inbuilt xml parsing tool. Please refere Apple document fir NSXMLParser,
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/Reference/Reference.html
http://developer.apple.com/library/mac/#documentation/cocoa/reference/NSXMLParserDelegate_Protocol/Reference/Reference.html
And also, if you receive your web-service response in JSON format, you can use SBJSON to parse the JSON files. You can get the json framework form this link,
https://github.com/stig/json-framework/
Thanks.
If you would like to know about different XML Parsers available and comparison between them, you can visit this tutorial which shows different xml parsers available and comparison between them.
I'm getting a large JSON string (11MB) from a web service. When I parse the data using JSONKit, my app reaches 70MB, I get memory warnings, and the app crashes.
How can I parse this data?
the easiest solution is reducing the json size you are getting from the server. If you cant to it, the only way to parse huge JSON is using lazy evaluation.
I dont think there is a JSON lib for objective-c that supports lazy evaluation. however you can implement one.
Your best bet is to look at the YAJL JSON parser, that supports event driven parsing. Then you can parse the JSON as it comes down in a data feed, and not have to store the whole thing in memory at once.
https://github.com/gabriel/yajl-objc
Sorry, I don't know of any code examples that demonstrate this use in practice.
SBJson supports parsing a stream of data. This lets your process your document bit by bit so you don't need to hold on to the entire document. The distribution contains two examples of how to use this. First there's the StreamParserIntegrationTest.m and next there's the TweetStream demo app: a twitter application that will sit and parse a HTTP stream all day (if you let it) displaying each tweet as they come in and then throw them away.
(Disclaimer: I am SBJson's author.)
11 mb is a largedata and solution is only to minimise your size of data
JSON support is not native to iOS, but there is a great framework for this exact purpose: http://code.google.com/p/json-framework/
This framework supports conversion from raw JSON objects to Objective-C objects (NSArray, NSDictionary) and vice versa.
Im building a new version of an iPhone application and Im wondering if I should review how my app communicates with the server.
My iPhone client sends and receives XML over HTTP requests.
To send the information I use ASIHTTPRequest framework. I "manually" build the XML request by appending strings.
To parse the response Im using a NSXMLParser.
My question is if I have better options to
A) Create an XML string from a memory object.
B) Create a memory object from the XML string.
Is there anything like JAXB to marshal XML into object?
Thanks
Gonso
Have a look TouchXml
http://code.google.com/p/touchcode/wiki/TouchXML
I'm not entirely sure if this would work for you, but you could try using JSON along with a JSON parser such as SBJSON, which will create an object in memory for you based on the data.
To get JSON from an XML feed, I believe you could send the request for XML to YQL(http://developer.yahoo.com/yql) which can then translate the feed into JSON before sending it back.
Parsing XML
I cant think of something that looks for tags and parses things directly into objects (for XML), but a standard line-by line parser does the job. It does require a lot of code to use NSXMLParser, so just set up an external class to do it. It doesn't take that long, and is easy to cancel [parser abortParsing]
I basically used a model in which it starts a parent element, gets the the data from detail elements and then when the parent element closes, the parser takes the temporary data, fills an object with it, and adds the object to an array. It then repeats the process. I don't think my way would be very effective if you had more that 3 levels of XML (root==>parent tags==>details tags within parents), but it works for me. If you have complex XML, I would find some way to switch over to JSON and use SBJSON like Matt.M suggested.
Creating XML
If I were creating XML, I would just use a bunch of for loops and one big NSMutableString.
I'm developing an iPhone app that is connected to a backend server. It needs to communicate with it many times, through several requests. I'm sending HTTP messages, but I want to receive more complex responses that I can parse somehow. Supposedly, I can provide any type of format for responses from the server, so my question is: which one would be easier(maybe even faster) to use/parse for Objective-C/Cocoa, and transform in a dictionary of some kind?
I know it's a bit subjective but I still think it's a valid question, some programming languages just have more support for some formats and less for others.
From Cocoa 's perspective, the simplest format is a property list as Cocoa can parse this natively into a dictionary or an array.
You can use NSDictionary's +dictionaryWithContentsOfFile: and +dictionaryWithContentsOfUrl: to read a plist file into a dictionary.
If your plist data is not in a file, you can also convert an NSData object containing plist data to a dictionary with +[NSPropertyListSerialization dataFromPropertyList:format:errorDescription:] or convert an NSString to a dictionary with -[NSString propertyList].
PList is a good answer and very usable, but many server side people will be more comfortable producing JSON - TouchJSON is a very good JSON parser for the iPhone.
While there is a plist gem for ruby, JSON or (raw) XML are much more popular outside the Apple world. For instance most JavaScript libraries are set up to speak one or both of these.
So if you're exclusively talking to an iPhone, the plist is probably a good choice, but otherwise you should consider using JSON (or XML).
We want to take XML data and convert it to an NSDictionary object, but we don't want to manually iterate over the XML. Is there an easy way to do this? How are you doing web services for your iPhone app?
If you have control over the XML output you could try creating a property list which you can then read into a dictionary using -dictionaryWithContentsOfURL: (though the better asynchronous way would be to get the data using an NSURLConnection and then converting the data using the -propertyList method on NSString). You can find more about property lists here: http://developer.apple.com/documentation/Cocoa/Conceptual/PropertyLists/Introduction/chapter_1_section_1.html
Of course the best solution is to use a RESTful client and use a combination of NSURLConnection to get/send the data and the TouchXML classes (http://code.google.com/p/touchcode/wiki/TouchXML) to parse the data, though this would require more work to put the data into a dictionary. Of course if these are going to be the main data objects in your system you really want to be using either a custom class or SQLite to store the data as it provides you much more reliability in testing your app than a dictionary.
If you can control the server output, try using plists. Otherwise you're stuck with parsing XML (or JSON if the server can do that), but there are frameworks you can use. See the answer to this question.
Also, here is a good overview of how to do RESTful clients on the iphone:
https://developer.apple.com/webapps/articles/creatingrestfulclients.html
You can return the data in JSON format. There are many open-source JSON parsers available for the iPhone (TouchJSON being one).
There's another class available called NSPropertyListSerialization which gets you a dictionary from data.
You can do something like this with the data you receive
NSDictionary* propertyList;
NSPropertyListFormat format;
NSString *errorStr;
propertyList = [NSPropertyListSerialization
propertyListFromData:receivedData
mutabilityOption: NSPropertyListImmutable
format: &format
errorDescription: &errorStr];
Sorry, don't know what tags are used here for formatting code!