iOS trying to get started with iPhone to server communication.

[jshmrsn]

Hi I posted this on Apple's forums also, but I never get responses there so I'd like to try here


I'd like my app to be able to communicate with my server, as many apps do.

Basically I have some PHP code that I'd like to run and get the output of.

I'm guessing I can execute the code with a hidden UIWebView's loadRequest, but I don't see how you would get the output.

I've never done this type of thing and would just like something I can start with.

Anything will help

Thanks,
Josh


Edit:
e.g. http://www.chalkboardapp.com/site/code_download/code_download.php

 

[DenNukem]

Start with this snippet and read up documentation on used classes:

	NSMutableURLRequest *rq = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:nssurl]];
	[rq setHTTPMethod: @"POST"];
	[rq setHTTPBody: nsdataInput];
    [rq setValue:@"text/xml" forHTTPHeaderField:@"Content-type"];
	NSError *err;
	NSHTTPURLResponse *response;
	NSData * nsdataReply = [NSURLConnection sendSynchronousRequest:rq returningResponse:&response error:&err];
	if(err!=Nil)
	{
		NSString * str = [err localizedDescription];

 

[jshmrsn]

Thanks a bunch for the help.

I also found this snippet which was very useful. (I happen to need GET more than POST, should have specified that)

NSString *FeedURL=@"http://www.google.com";
NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:FeedURL]];
NSURLResponse *resp = nil;
NSError *err = nil;
NSData *response = [NSURLConnection sendSynchronousRequest: theRequest returningResponse: &resp error: &err];
NSString * theString = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding]; 

NSLog(@"response: %@", theString);
editorTextView.text = theString;

Thanks again,
Josh

 

[kainjow]

Don't use sendSynchronousRequest as it blocks the current thread. Use initWithRequest:delegate: (or similar methods) to start an asynchronous connection which runs in a separate thread.

 

[Nutter]

Also, sendSynchronousRequest leaks like crazy. Difficult to believe, but true.

 

[jshmrsn]

Oh okay, thanks.

I was wondering how to go about async.

 

[rafaelfaria]

Server to Iphone communication

Is there a way to do the other way around? Like... the server send some message to the iphone?

I still cant give any details what i'm thinking b to develop but it would be something like a emial client.

I will send an email to a server, the server find my iphone and notify me that i have a message.

Is there any way to do that?

 

[robbieduncan]

Is there a way to do the other way around? Like... the server send some message to the iphone?

I still cant give any details what i'm thinking b to develop but it would be something like a emial client.

I will send an email to a server, the server find my iphone and notify me that i have a message.

Is there any way to do that?

Not yet. Once 2.1 is released and the push framework is opened up to third part developers there will be...

 

[jsnuff1]

I was trying to do the same thing...thanks for the info.

So i figured out how to get the data from the server, and have the data in a String

The data itself is a xml document that contains about 50 of the fallowing

<item>
<title>Data1 = (3.167963)</title>
<link></link>
<description></description>
<pubDate>Tue, 12 Aug 2008 13:20:01 CST</pubDate>
</item>
<item>
<title>Data2 = (2.115675)</title>
<link></link>
<description></description>
<pubDate>Tue, 12 Aug 2008 13:20:01 CST</pubDate>
</item>

and so on

so how do i go about retrieving the number in the parenthesis? What i will end up doing is creating an array with all 50 of these numbers, but I have no idea how to actually access a specific number in that string.

 

[jsnuff1]

ok i have half answered my own question

after I get the String I do this to find the specific number i need


NSRange range = [theString rangeOfString"DATA1"];
unichar *buffer;

range.length = range.length + 3;
range.location = range.location + 7;
[theString getCharacters:buffer range:range];

NSString *subString = [[[NSString alloc] initWithCharacters:buffer length:range.length] autorelease];


NSLog(@"response: %@", subString);


I see that the exact number i need is correctly stored in subString from the NSLog message, but after this the program crashes. I think im not doing something correctly with the buffer and getCharacter method.

 

[robbieduncan]

Why are you using the buffer etc? Why not use substringWithRange:?

 

[jsnuff1]

thanks...that was easy.

 

[jsnuff1]

Now that I got everything working ive encountered another little problem. The program works fine when there is a good internet connection. Once the internet gets spotty (especially with bad cell reception) the program crashes after trying to load data from the server.

I was hopeing NSURLConnection would return a nil object if there was a problem with the internet connection and not bring down the whole program, but I guess it throws some sort of exception?

It works fine when there is NO internet connection (and I have handled for this case in my program) but how do I handle a spotty internet connection. I dont even know what NSURLConnection returns in this case. I know the program crashes about 10 seconds after initilizing the connection, so maybe its some sort of timeout error?

 

[robbieduncan]

You need to pass an address via the (NSError **) error parameter and check it after the call.