challenge

[dmelgoza]

Okay,
so, I've spent days trying to connect to

http://weather.yahooapis.com/forecastrss?w=12791977

, parse the information find the weather condition which is in the element "yweather" under "code" (which is a number that means a diff. weather cond.)

Based on that I want to create a conditional statement that would be something like

//makes the cloud image appear on my view controller
if (code = 34){
[cloudy setHidden: NO];
}

Obviously, since I am posting in this site, it's not working. I challenge y'all to figure this out cause this is killing me. Before you think I'm creating another Weather app, let me assure you that this will only be a small feature on my otherwise complete app.

This is the code in my ViewController.m

- (void)openXMLFile{
	NSString * path = @"http://weather.yahooapis.com/forecastrss?w=12791977";
	[self parseXMLFile:path];
	
}


- (void)parseXMLFile:(NSString *)path
{	
	BOOL success;
	
    //you must then convert the path to a proper NSURL or it won't work
    NSURL *xmlURL = [NSURL URLWithString:path];
	
	if (rssParser)
		[rssParser release];
	
    // here, for some reason you have to use NSClassFromString when trying to alloc NSXMLParser, otherwise you will get an object not found error
    // this may be necessary only for the toolchain
    rssParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL];
	
	
    // Set self as the delegate of the parser so that it will receive the parser delegate methods callbacks.
    [rssParser setDelegate:self];
	
    // Depending on the XML document you're parsing, you may want to enable these features of NSXMLParser.
    
    [rssParser setShouldResolveExternalEntities:YES];
	
	success = [rssParser parse];
	
	
	
    //[rssParser parse];
	
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{			
    //NSLog(@"found this element: %@", elementName);
	

	if ([elementName isEqualToString:@"yweather"]) {
		
		NSString* title = [attributeDict valueForKey:@"text"];    
		int id = [[attributeDict valueForKey:@"code"] intValue];
		NSLog(@"Title: %@, ID: %i", title, id);
		NSLog(@"This is the NS LOG 3");
	}
	
	
	
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{     

	
	
}

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

	
}

[RobotWoods]

I may use PHP as too much of a crutch, but you could use a PHP scraper to grab the item you need, and then instead of accessing the page you indicated directly and trying to parse it out, just hit your PHP for the data directly...

something like:

PHP Code:

<?php
$url="http://weather.yahooapis.com/forecastrss?w=12791977";
$file=file_get_contents($url);
$start=strpos($file,'code=');
$data=substr($file, $start+6, 2);
echo $data;
?>

and then:

PHP Code:

NSString *weatherURL = [ NSString stringWithFormat: @"http://thatfile.php"];
NSData *weatherData = [NSData dataWithContentsOfURL:[NSURL URLWithString:weatherURL]];
NSString *weatherString = [[NSString alloc] initWithBytes: [weatherData bytes] length:[weatherData length] encoding: NSUTF8StringEncoding];
int code;
code = [weatherString intValue]; 


[dmelgoza]

Okay, so I created the php file it returns 34 when viewed in the browser

but my conditional statement wasn't working right, so I tried NSlogging "code" and it came out "condition is: (null)" in the console.

NSString *weatherURL = [ NSString stringWithFormat: @"http://www.etzmedia.com/iphone/parse.php"];
	 NSData *weatherData = [NSData dataWithContentsOfURL:[NSURL URLWithString:weatherURL]];
	 NSString *weatherString = [[NSString alloc] initWithBytes: [weatherData bytes] length:[weatherData length] encoding: NSUTF8StringEncoding];
	 int code;
	 code = [weatherString intValue];  
	 NSLog(@"condition is: %@", code);
	 
	 if (code = 12){
		 //NSLog(@"code is 34");
	 }
	 else
	 {
		//NSLog(@"code is not 34"); 
	 //[cloudy setHidden:YES];
	 }
 }

something is not connecting right, any ideas?

[Robert Paulson]

In your code it says,

	 if (code = 12){
		 //NSLog(@"code is 34");
	 }

you check for 12 but report 34. Is that intended?

For the other NSLog call, you may want to use %i or %d instead of %@ since you want to log an integer, not an object. I am new to Obj-C and everything iPhone related so I don't really know whether that is the reason for your (null).

NSLog(@"condition is: %i", code);

Cheers,
Bob

[Kalimba]

Looking at the XML returned from that URL, I'm seeing this as the element containing the 'code' attribute:

<yweather:condition  text="Fair"  code="34"  temp="62"  date="Wed, 28 Apr 2010 8:53 am CDT" />

so I believe you should be checking for an element named "yweather:condition", not just "yweather".

Your code to obtain the value of the "code" attribute looks fine, but the condition in your 'if' statement is wrong. You're doing this:

if ( code = 34 )
{
   blah blah blah...
}

where you should be doing this:

if ( code == 34 ) // '==' is the test for equality operator
{
   blah blah blah...
}

So, to wrap up, you probably want your code to look something like this:

if ( [elementName isEqualToString:@"yweather:condition"] )
{
	NSString * title = [attributeDict valueForKey:@"text"];    
	int id = [[attributeDict valueForKey:@"code"] intValue];
	NSLog(@"Title: %@, ID: %i", title, id);
}

[dmelgoza]

guys it totally worked! not so thrilled about having to use php, BUT it worked so who cares???!!!!!

Haha!

It's amazing how php did in 4-5 lines, what takes objective C a whole lot more.

[Kalimba]

Originally Posted by dmelgoza

...It's amazing how php did in 4-5 lines, what takes objective C a whole lot more.

You're comparing apples and oranges and clearly don't understand what the PHP does versus what the Obj-C code does. That PHP code does "in 4-5 lines" the very specific task of finding a particular sequence of letters and returning a fixed number of characters that follow. So if your XML looks like this:

<yweather:condition ... code="34" ... />

you should be OK. But if the XML ever looks like any of the following, your magical PHP code will suddenly be returning strange values:

<yweather:condition ... code="6" ... />

or

<yweather:condition ... code="125" ... />

or

<yweather:condition ... code= "34" ... />

or

<yweather:condition ... code ="34" ... />

[RobotWoods]

Kalimba is right, using this as an intermediate is a brittle system...this will give you a bit more latitude if there is a minor syntax change (but still assumes no blank spaces within the quotes):

PHP Code:

<?php
$url="http://weather.yahooapis.com/forecastrss?w=12791977";
$file=file_get_contents($url);
$item=strpos($file,'<yweather:condition');
$start=strpos($file,'code',$item);
$open=strpos($file,'\"',$start);
$close=strpos($file,'\"',$open+1);
$data=substr($file, $open+1,$close-$open-1);
echo $data;
?>