iPhone编码：从XML文件接收数据并要保存到SQLite

Question

i am trying to setup a iPhone app that pulls XML file from the internet and then want it to save to a SQLite database. the coding i am using to parser the XML file is:

SQLViewAppDelegate.m

NSURL *url = [[NSURL alloc] initWithString:@"http://www.180designlab.com/waxjambu/getupdates.xml"];
NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url];
XMLParser *parser = [[XMLParser alloc] initXMLParser];
[xmlParser setDelegate:parser];
BOOL success = [xmlParser parse];
NSLog(@"Info array has %d items", [infoGet count]);
totalCount = [infoGet count];
//[self save_Clicked];

if(success)
  NSLog(@"No Errors");
else 
  NSLog(@"Error Error Error");

XMLParser.m

-(XMLParser *)initXMLParser
{

[super init];
appDelegate = (SQLViewAppDelegate *)[[UIApplication sharedApplication] delegate];

return self;
}

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict
{


if ([elementName isEqualToString:@"Updates"]) 
{


appDelegate.infoGet = [[NSMutableArray alloc] init];


}


else if ([elementName isEqualToString:@"Update"])
{
            aInfo = [[XMLInfo alloc] init];
    aInfo.infoGetID = [[attributeDict objectForKey:@"id"] integerValue];

    //aGetInfo.info
    NSLog(@"Info ID Value: %i", aInfo.infoGetID);
}



NSLog(@"Processing Element: %@", elementName);

}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

 {



if(!currentElementValue)
    currentElementValue = [[NSMutableString alloc] initWithString:string];
  else 
    [currentElementValue appendString:string];
    //[self saveData];
    NSLog(@"Processing Value: %@", currentElementValue);
    NSLog(@"Processing ID: %d", aInfo.infoGetID);

}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName

 {

if ([elementName isEqualToString:@"Updates"])
    return;
    if ([elementName isEqualToString:@"Update"]) 

{


[appDelegate.infoGet addObject:aInfo];

        [aInfo release];
        aInfo = nil;


}

else
    [aInfo setValue:currentElementValue forKey:elementName];
    [currentElementValue release];
    currentElementValue = nil;

}

I can get the data in to a tableView but can not work out how to save them to SQLite file I have up.

I can load data to a tableView from the SQLite file fine as well.. I also now how add to SQLite when using a AddView when you enter data in two textfields. what ever I try it comes up saying out of memory. I know it be something simple but just cant fine or work this out.

hope someone can help me with this.

I look forward in hearing back from you

Answer 1

Regarding your memory issue. Have you released all your objects? Any time you type Alloc , New or Copy , you are responsible for that object and must release it at some stage in your code.

Instead of SQLite, use Core Data. Core Data uses SQLite as its backing store and stores data in an object-orientated way.

You need to select the checkbox for Core Data when creating a project.

Querying Core Data is done as follows:

NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = [NSEntityDescription entityForName:@"TABLENAME" inManagedObjectContext:context];
request.predicate = [NSPredicate predicateWithFormat:@"uniqueId = %@", [Data objectForKey:@"id"]];

NSError *error = nil;
NSManagedContext *returnedData = [[context executeFetchRequest:request error:&error] lastObject];
[request release];

Inserting data is done as follows:

[NSEntityDescription insertNewObjectForEntityForName:@"TABLENAME" inManagedObjectContext:context];
    MODEL_OBJECT.uniqueId = [Data objectForKey:@"id"];
    MODEL_OBJECT.title = [Data objectForKey:@"title"];

For a great example, watch lecture 12 (Core data and Table Views) from Stanford's Developing Apps for iOS iTunes U module.

• MODEL_OBJECT would be the NSManagedObject entity object that is automatically created when you create your NSManagedObjects.

Apologise if this doesn't answer your question, but using Core Data is much more efficient than SQL for iPhone Apps.