Daan Luttik Daan Luttik - 3 months ago 19
iOS Question

Sending an HTTP POST request on iOS

I'm trying to send an HTTP Post with the iOS application that I'm developing but the push never reaches the server although I do get a code 200 as response (from the urlconnection). I never get a response from the server nor does the server detect my posts (the server does detect posts coming from android)

I do use ARC but have set pd and urlConnection as strong.

This is my code for sending the request

NSMutableURLRequest *request = [[NSMutableURLRequest alloc]
initWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@%@",dk.baseURL,@"daantest"]]];
[request setHTTPMethod:@"POST"];
[request setValue:@"text/xml"
forHTTPHeaderField:@"Content-type"];

NSString *sendString = @"<data><item>Item 1</item><item>Item 2</item></data>";

[request setValue:[NSString stringWithFormat:@"%d", [sendString length]] forHTTPHeaderField:@"Content-length"];

[request setHTTPBody:[sendString dataUsingEncoding:NSUTF8StringEncoding]];
PushDelegate *pushd = [[PushDelegate alloc] init];
pd = pushd;
urlConnection = [[NSURLConnection alloc] initWithRequest:request delegate:pd];
[urlConnection start];


this is my code for the delegate

#import "PushDelegate.h"

@implementation PushDelegate
@synthesize data;

-(id) init
{
if(self = [super init])
{
data = [[NSMutableData alloc]init];
[data setLength:0];
}
return self;
}


- (void)connection:(NSURLConnection *)connection didWriteData:(long long)bytesWritten totalBytesWritten:(long long)totalBytesWritten
{
NSLog(@"didwriteData push");
}
- (void)connectionDidResumeDownloading:(NSURLConnection *)connection totalBytesWritten:(long long)totalBytesWritten expectedTotalBytes:(long long)expectedTotalBytes
{
NSLog(@"connectionDidResumeDownloading push");
}

- (void)connectionDidFinishDownloading:(NSURLConnection *)connection destinationURL:(NSURL *)destinationURL
{
NSLog(@"didfinish push @push %@",data);
}

- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
{
NSLog(@"did send body");
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[self.data setLength:0];
NSHTTPURLResponse *resp= (NSHTTPURLResponse *) response;
NSLog(@"got response with status @push %d",[resp statusCode]);
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)d
{
[self.data appendData:d];

NSLog(@"recieved data @push %@", data);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *responseText = [[NSString alloc] initWithData:self.data encoding:NSUTF8StringEncoding];

NSLog(@"didfinishLoading%@",responseText);

}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
[[[UIAlertView alloc] initWithTitle:NSLocalizedString(@"Error ", @"")
message:[error localizedDescription]
delegate:nil
cancelButtonTitle:NSLocalizedString(@"OK", @"")
otherButtonTitles:nil] show];
NSLog(@"failed &push");
}

// Handle basic authentication challenge if needed
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
NSLog(@"credentials requested");
NSString *username = @"username";
NSString *password = @"password";

NSURLCredential *credential = [NSURLCredential credentialWithUser:username
password:password
persistence:NSURLCredentialPersistenceForSession];
[[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
}

@end


The console always prints the following lines and the following lines only:

2013-04-01 20:35:04.341 ApprenticeXM[3423:907] did send body
2013-04-01 20:35:04.481 ApprenticeXM[3423:907] got response with status @push 200
2013-04-01 20:35:04.484 ApprenticeXM[3423:907] didfinish push @push <>

Answer

The following code describes a simple example using POST method.(How one can pass data by POST method)

You can use the following code snippet, as described in this article:

Here, I describe how one can use of POST method.

1. Set post string with actual username and password.

NSString *post = [NSString stringWithFormat:@"Username=%@&Password=%@",@"username",@"password"]; 

2. Encode the post string using NSASCIIStringEncoding and also the post string you need to send in NSData format.

NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES]; 

You need to send the actual length of your data. Calculate the length of the post string.

NSString *postLength = [NSString stringWithFormat:@"%d",[postData length]]; 

3. Create a Urlrequest with all the properties like HTTP method, http header field with length of the post string. Create URLRequest object and initialize it.

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init]; 

Set the Url for which your going to send the data to that request.

[request setURL:[NSURL URLWithString:@"http://www.abcde.com/xyz/login.aspx"]]; 

Now, set HTTP method (POST or GET). Write this lines as it is in your code.

[request setHTTPMethod:@"POST"]; 

Set HTTP header field with length of the post data.

[request setValue:postLength forHTTPHeaderField:@"Content-Length"]; 

Also set the Encoded value for HTTP header Field.

[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];

Set the HTTPBody of the urlrequest with postData.

[request setHTTPBody:postData];

4. Now, create URLConnection object. Initialize it with the URLRequest.

NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self]; 

It returns the initialized url connection and begins to load the data for the url request. You can check that whether you URL connection is done properly or not using just if/else statement as below.

if(conn) {
    NSLog(@"Connection Successful");
} else {
    NSLog(@"Connection could not be made");
}

5. To receive the data from the HTTP request , you can use the delegate methods provided by the URLConnection Class Reference. Delegate methods are as below.

// This method is used to receive the data which we get using post method.
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data

// This method receives the error report in case of connection is not made to server. 
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 

// This method is used to process the data after connection has made successfully.
- (void)connectionDidFinishLoading:(NSURLConnection *)connection

Also Refer This and This documentation for POST method.

And here is best example with source code of HTTPPost Method.