How to download CSV file from server in Objective-C - iphone

Question

I'm developing a new iPhone application, Here i have parsed a 'csv' file from local, and its working with me. When i try to download the 'csv' file from the server programmatically, it didn't workout for me. Could you please help me?
Loading data from local file (Working fine)
- (void)viewDidLoad
{
[super viewDidLoad];
NSString * file = [[NSBundle bundleForClass:[self class]] pathForResource:#"sample" ofType:#"csv"];
NSStringEncoding encoding = 0;
NSString * csv = [NSString stringWithContentsOfFile:file usedEncoding:&encoding error:nil];
NSArray *fields = [csv CSVComponents];
NSLog(#"fields: %#", fields); //getting the result content
}
Download the file from Server (failed)
-(void) connectionDidFinishLoading:(NSURLConnection *)connection
{
NSLog(#"connectionDidFinishLoading"); //nothing showing here
NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *fullName = [NSString stringWithFormat:#"quotes.csv"];
NSString *fullFilePath = [NSString stringWithFormat:#"%#/%#",docDir,fullName];
[receivedData writeToFile:fullFilePath atomically:YES];
}
-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
NSLog(#"data: %#", data); //nothing showing here
if (receivedData)
[receivedData appendData:data];
else
receivedData = [[NSMutableData alloc] initWithData:data];
}
- (void)loadDatafromURL
{
NSURL *url = [NSURL URLWithString:#"http://download.finance.yahoo.com/d/quotes.csv?s=^GSPC,^IXIC,^dji,^GSPC,^BVSP,^GSPTSE,^FTSE,^GDAXI,^FCHI,^STOXX50E,^AEX,^IBEX,^SSMI,^N225,^AXJO,^HSI,^NSEI&f=sl1d1t1c1ohgv&e=.csv"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection connectionWithRequest:request delegate:self];
}

Answer 1

Implement this method:
-(void)connection:(NSURLConnection *)conn didFailWithError:(NSError *)error
You'll find that you're getting an error of
Error Domain=NSURLErrorDomain Code=-1000 "bad URL" UserInfo=0xf663f40 {NSUnderlyingError=0xf663de0 "bad URL", NSLocalizedDescription=bad URL}
I've looked into downloading information this way before, and I think one problem you're having is that separate symbols have to be separated with a "+". Also, when pulling an index, you can't pass the "^" symbol as part of the URL. You have to replace it with "%5E".
So, add this:
- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
NSLog(#"%#", [error description]);
}
And change your URL to this:
NSString *urlString = #"http://download.finance.yahoo.com/d/quotes.csv?s=^GSPC+^IXIC+^dji+^GSPC+^BVSP+^GSPTSE+^FTSE+^GDAXI+^FCHI+^STOXX50E+^AEX+^IBEX+^SSMI+^N225+^AXJO+^HSI+^NSEI&f=sl1d1t1c1ohgv&e=.csv";
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]];
Now it works for me! I even checked the output .csv file, and it looks good to go! One full quote per line.

Answer 2

If you plan on fetching more data over the network than this single csv, you could have a look at AFNetworking, it's a great library for doing network operations.
A working solution would then look a bit like this:
- (void)getCSVAsynch {
NSString *unescaped = #"http://download.finance.yahoo.com/d/quotes.csv?s=^GSPC,^IXIC,^dji,^GSPC,^BVSP,^GSPTSE,^FTSE,^GDAXI,^FCHI,^STOXX50E,^AEX,^IBEX,^SSMI,^N225,^AXJO,^HSI,^NSEI&f=sl1d1t1c1ohgv&e=.csv";
NSURL *url = [NSURL URLWithString:[unescaped stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"CSV: %#", [[NSString alloc] initWithBytes:[responseObject bytes] length:[responseObject length] encoding:NSUTF8StringEncoding]);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Things go boom. %#", [error localizedDescription]);
}];
[operation start];
}