A Reusable Cocoa REST Client

It wasn’t too difficult to build a REST client in Cocoa for my iPhone app, but there was enough to it that I wanted to wrap it in a service, so I could make a REST call in one line. And so I could reuse it and pass it along to you!

Download a zip file containing the header and class file, or see the code below.

Incidentally, if you’re wondering how I create/consume the data, I use json-framework. It’s very easy to integrate into your project, and converts JSON objects to/from NSMutableDictionaries / NSMutableArrays.

Usage

Note: I haven’t tested this exact usage code, so you may need to tweak it.

RestService *svc = [[RestService alloc] init];
NSHTTPURLResponse *response = nil;

// simplest request: GET, no headers
NSString *result = [svc requestToUrl:@"http://..."
                            response:&response];
NSLog(@"status code: %d", response.statusCode);
NSLog(@"content: %@", result);

// most complex request: all parameters
NSDictionary headers = [NSDictionary dictionaryWithObjectsAndKeys:
                           @"application/json", @"Content-Type"
                           @"Basic ...", @"Authorization",
                           nil];
NSString *requestBody = @"some xml or json";
NSString *result = [svc requestToUrl:@"http://..."
                              method:METHOD_POST
                                body:requestBody
                             headers:headers
                            response:&response];
NSLog(@"status code: %d", response.statusCode);
NSLog(@"content: %@", result);

RestService.h

//
//  RestService.h
//  TypeLinkNav
//
//  Created by Josh Justice on 10/21/10.
//  Copyright 2010 Josh Justice. All rights reserved.
//

#import 

#define METHOD_GET @"GET"
#define METHOD_PUT @"PUT"
#define METHOD_POST @"POST"
#define METHOD_DELETE @"DELETE"

@interface RestService : NSObject {

}

-(NSString *)requestToURL:(NSString *)url
				 response:(NSHTTPURLResponse **)response;

-(NSString *)requestToURL:(NSString *)url
				  headers:(NSDictionary *)headers
				 response:(NSHTTPURLResponse **)response;

-(NSString *)requestToURL:(NSString *)url
				   method:(NSString *)method
				  headers:(NSDictionary *)headers
				 response:(NSHTTPURLResponse **)response;

-(NSString *)requestToURL:(NSString *)url
				   method:(NSString *)method
					 body:(NSString *)body
				  headers:(NSDictionary *)headers
				 response:(NSHTTPURLResponse **)response;

@end

RestService.m

//
//  RestService.m
//  TypeLinkNav
//
//  Created by Josh Justice on 10/21/10.
//  Copyright 2010 Josh Justice. All rights reserved.
//

#import "RestService.h"

@implementation RestService

-(NSString *)requestToURL:(NSString *)url
				 response:(NSHTTPURLResponse **)response
{
	return [self requestToURL:url
					  headers:nil
					 response:response];
}

-(NSString *)requestToURL:(NSString *)url
				  headers:(NSDictionary *)headers
				 response:(NSHTTPURLResponse **)response
{
	return [self requestToURL:url
					   method:METHOD_GET
					  headers:headers
					 response:response];
}

-(NSString *)requestToURL:(NSString *)url
				   method:(NSString *)method
				  headers:(NSDictionary *)headers
				 response:(NSHTTPURLResponse **)response
{
	return [self requestToURL:url
					   method:method
						 body:nil
					  headers:headers
					 response:response];
}

-(NSString *)requestToURL:(NSString *)urlString
				   method:(NSString *)method
					 body:(NSString *)body
				  headers:(NSDictionary *)headers
				 response:(NSHTTPURLResponse **)response
{
	// create the url
	NSURL *url = [NSURL URLWithString:urlString];

	NSLog(@"requesting %@, %@",method,url);
	NSLog(@"request body: %@", body);

	NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

	// set up the request
	if( nil != method ) {
		[request setHTTPMethod:method];
	}
	if( nil != body ) {
		NSData *bodyData = [body dataUsingEncoding:NSASCIIStringEncoding];
		[request setHTTPBody:bodyData];
	}
	if( nil != headers ) {
		NSEnumerator *e = [headers keyEnumerator];
		NSString *headerName;
		while( headerName = [e nextObject] ) {
			[request setValue:[headers objectForKey:headerName]
		   forHTTPHeaderField:headerName];
		}
	}

	// get the response
	NSHTTPURLResponse *myResponse = NULL;
	NSError *error = NULL;
	NSData *resultData = [NSURLConnection sendSynchronousRequest:request
										 returningResponse:&myResponse
													 error:&error];
	// pass response object back to user by reference
	*response = myResponse;

	// convert response body to string
	NSString *resultString = [[NSString alloc] initWithData:resultData
												   encoding:NSASCIIStringEncoding];
	NSLog(@"response body: %@", resultString);
	return resultString;
}

@end

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