Question

I’m building an application that parses XML from an online server. I want to cache the XML file locally for 24 hours. How can I change the following code to read from a file in my resource directory?

parser = [[NSXMLParser alloc] initWithContentsOfURL: [NSURL URLWithString:url]];

Answer 1

You can obtain the path for your xml file like the following:

NSString* path = [[NSBundle mainBundle] pathForResource:@"yourxml" ofType:@"xml"];

and then obtain a NSData instance like the following:

NSData *xmlData = [[NSMutableData alloc] initWithContentsOfFile:path];

and finally call

initWithData method of NSXMLParser.

But you cannot modify the content of your application bundle. Files in the bundle (the resources directory you asked for) cannot be modified.

There are different way to do it:

• grab the file from the web and save it in a property-list file
• use NSFileManager class to save and read your xml file

An example with NSFileManager:

NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* documentsDirectoryPath = [paths objectAtIndex:0];
NSString* filePath = [documentsDirectoryPath stringByAppendingPathComponent:@"yourxml.xml"];

The snippet grab the xml file path contained in your Documents directory. It means that there is already a file there. For further info see NSFileManager class and how-to-save-your-app-data-with-nscoding-and-nsfilemanager

Hope it helps.