In this article we will see some basic things about web services and then learn how to call SOAP web service from iOS application.
What is a web service?
Web service is basically an application programming interface (API) which is accessed by HTTP. In other language web services are application components which can communicate using open protocols.
How does web services work?
XML HTTP is the basic web service platform.
XML is the language that can be used between different platforms and programming languages.
HTTP is the most used internet protocol.
What are the Web services platform elements?
SOAP (Simple Object Access Protocol)
WSDL (Web Services Description Language)
UDDI (Universal Description, Discovery and Integration)
What is SOAP?
SOAP stands for Simple Object Access Protocol. SOAP is an XML-based protocol for accessing a Web Service and let applications exchange information over HTTP.
So above were the basic things to understand about web services and SOAP. Now let’s see how we can call SOAP web services from iOS application.
Steps to call SOAP web services from iOS apps
In the example below, I have used CelsiusToFahrenheit SOAP web service provided by W3Schools.
1) Create a string with SOAP request.
2) Create NSMutableRequest with request URL.
Here we can send post data in message body which can be received by server from the web service request set by iOS application.
NSURL *sRequestURL = [NSURL URLWithString:@"http://w3schools.com/webservices/tempconvert.asmx"];
NSMutableURLRequest *myRequest = [NSMutableURLRequest requestWithURL:sRequestURL];
NSString *sMessageLength = [NSString stringWithFormat:@"%d", [sSOAPMessage length]];
[myRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
[myRequest addValue: @"http://www.w3schools.com/webservices/CelsiusToFahrenheit" forHTTPHeaderField:@"SOAPAction"];
[myRequest addValue: sMessageLength forHTTPHeaderField:@"Content-Length"];
[myRequest setHTTPMethod:@"POST"];
[myRequest setHTTPBody: [sSOAPMessage dataUsingEncoding:NSUTF8StringEncoding]];
NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:myRequest delegate:self];
if( theConnection ) {
self.webResponseData = [[NSMutableData data] retain];
}else {
NSLog(@"Some error occurred in Connection");
}
3) Get XML response in NSURLConnections delegate methods.
Objective-C
-(void)connection:(NSURLConnection)connection didReceiveResponse:(NSURLResponse)response { [self.webResponseData setLength:0]; }
-(void)connection:(NSURLConnection)connection didReceiveData:(NSData)data { [self.webResponseData appendData:data]; }
-(void)connection:(NSURLConnection)connection didFailWithError:(NSError)error { NSLog(@"Some error in your Connection. Please try again."); }
-(void)connectionDidFinishLoading:(NSURLConnection)connection { NSLog(@"Received Bytes from server: %d", [self.webResponseData length]); NSStringmyXMLResponse = [[NSString alloc] initWithBytes: [self.webResponseData bytes] length:[self.webResponseData length] encoding:NSUTF8StringEncoding]; NSLog(@"%@",myXMLResponse); }
-(void)connection:(NSURLConnection)connection didReceiveResponse:(NSURLResponse)response { [self.webResponseData setLength:0]; }
-(void)connection:(NSURLConnection)connection didReceiveData:(NSData)data { [self.webResponseData appendData:data]; }
-(void)connection:(NSURLConnection)connection didFailWithError:(NSError)error { NSLog(@"Some error in your Connection. Please try again."); }
-(void)connectionDidFinishLoading:(NSURLConnection)connection { NSLog(@"Received Bytes from server: %d", [self.webResponseData length]); NSStringmyXMLResponse = [[NSString alloc] initWithBytes: [self.webResponseData bytes] length:[self.webResponseData length] encoding:NSUTF8StringEncoding]; NSLog(@"%@",myXMLResponse); } So here we are done with web service call and also got final response data in the delegate method connectionDidFinishLoading. In the above example we will receive the response in XML format. We can use some APIs like TBXML, KissXML etc… to parse response XML and get data to use in the application.
I hope this article was easy to understand on how to send / receive data using SOAP web services from iOS application. You can post your comments and queries in the comment box given below.
原文出自:
http://www.technetexperts.com/mobile/how-to-access-soap-web-services-from-ios-sdk/
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