Simple JSONAPI implementation for Bukkit servers

JSONAOPIClient.h

//
//  JSONAOPIClient.h
//
//  Created by Mykola Stukalo on 10.04.14.
//

#import <Foundation/Foundation.h>

@interface JSONAPIClient : NSObject

- (void)runServerCommandWithArguments:(NSArray*)arguments;
- (void)runAPIMethod:(NSString*)command arguments:(NSArray*)arguments;

@end

JSONAOPIClient.m

//
//  JSONAOPIClient.m
//
//  Created by Mykola Stukalo on 10.04.14.
//

#import "JSONAPIClient.h"
#import "AFNetworking.h"
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonHMAC.h>

static NSString * const kHost = @"hostname";
NSInteger const kPort = 20059;
static NSString * const kUsername = @"username";
static NSString * const kPassword = @"password";

static NSString * const kURLFormat = @"http://%@:%li/api/2/call?json=%@";

@implementation JSONAPIClient

- (void)runServerCommandWithArguments:(NSArray*)arguments;
{
    [self runAPIMethod:@"server.run_command" arguments:arguments];
}

- (void)runAPIMethod:(NSString*)command arguments:(NSArray*)arguments
{
    NSURL *URL = [self URLforMethod:command arguments:arguments];
    
    NSLog(@"url %@", URL);
    
    if (!URL)
    {
        NSLog(@"Failed to create URL for server command with arguments %@", arguments);
        return;
    }
    
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    manager.requestSerializer = [AFJSONRequestSerializer serializer];
    manager.responseSerializer = [AFJSONResponseSerializer serializer];
    
    [manager GET:URL.absoluteString parameters:nil
         success:^(AFHTTPRequestOperation *operation, id responseObject)
     {
         NSLog(@"%@", responseObject);
         
     } failure:^(AFHTTPRequestOperation *operation, NSError *error)
     {
         NSLog(@"Failure %@", error);
     }];
}

- (NSString*)keyForMethod:(NSString*)method
{
    NSString *keyString = [NSString stringWithFormat:@"%@%@%@", kUsername, method, kPassword];
    
    return [self sha256StringFromString:keyString];
}

- (NSString*)sha256StringFromString:(NSString*)aString
{
    const char *string = aString.UTF8String;
	int length = (int)strlen(string);
	unsigned char bytes[CC_SHA256_DIGEST_LENGTH];
	CC_SHA256(string, length, bytes);
	return [self stringFromBytes:bytes length:CC_SHA256_DIGEST_LENGTH];
}

- (NSString *)stringFromBytes:(unsigned char *)bytes length:(int)length
{
	NSMutableString *mutableString = @"".mutableCopy;
	for (int i = 0; i < length; i++)
		[mutableString appendFormat:@"%02x", bytes[i]];
	return [NSString stringWithString:mutableString];
}

- (NSDictionary*)jsonCallForMethod:(NSString*)method arguments:(NSArray*)arguments
{
    NSMutableDictionary *dictionary = [@{@"name" : method,
                                        @"key" : [self keyForMethod:method],
                                        @"username" : kUsername} mutableCopy];
    
    if (arguments)
    {
        dictionary[@"arguments"] = arguments;
    }
    else
    {
        dictionary[@"arguments"] = [NSArray array];
    }
    
    return dictionary;
}

- (NSURL*)URLforMethod:(NSString*)method arguments:(NSArray*)arguments
{
    NSDictionary *jsonCall = [self jsonCallForMethod:method arguments:arguments];
    if (![NSJSONSerialization isValidJSONObject:jsonCall]) return nil;
    
    NSError *error = nil;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonCall options:0 error:&error];
    
    if (error)
    {
        NSLog(@"Failed to serialize JSON data %@ with error %@", jsonCall, error);
        return nil;
    }
    
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    NSLog(@"jsonString %@", jsonString);
    NSMutableCharacterSet *characterSet = [NSMutableCharacterSet alphanumericCharacterSet];
    [characterSet addCharactersInString:@"="];
    jsonString = [jsonString stringByAddingPercentEncodingWithAllowedCharacters:characterSet];
    NSString *URLString = [NSString stringWithFormat:kURLFormat, kHost, (long)kPort, jsonString];
    return [NSURL URLWithString:URLString];
}

@end