sig sign for POST methods

SignRequest.h

//
//  SignRequest.h
//  CryptClassPro
//
//  Created by VITALIY PODOLSKIY on 01/08/15.
//  Copyright © 2015 VITALIY PODOLSKIY. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface SignRequest : NSObject

+ (SignRequest *)sharedRequest;

- (NSString *)signRequest:(NSDictionary *)params;

@end

SignRequest.m

//
//  SignRequest.m
//  CryptClassPro
//
//  Created by VITALIY PODOLSKIY on 01/08/15.
//  Copyright © 2015 VITALIY PODOLSKIY. All rights reserved.
//

#import "SignRequest.h"
#import "NSString+SHA256HMAC.h"

@implementation SignRequest

+ (SignRequest *)sharedRequest {
    
    static SignRequest *_sharedRequest = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedRequest = [[SignRequest alloc] init];
    });
    return _sharedRequest;
} // sharedRequest


- (NSString *)signRequest:(NSDictionary *)params {
    
    NSDictionary *signDictionary = params;
    NSMutableString *sigString = [[NSMutableString alloc] init];
    // add endpoint
    NSString *endpoint = [signDictionary valueForKey:@"endpoint"];
    if (endpoint) {
        [sigString appendString:endpoint];
    }
    //add access_token
    NSString *access_token = [signDictionary valueForKey:@"access_token"];
    if (access_token) {
        [sigString appendString:[NSString stringWithFormat:@"|access_token=%@", access_token]];
    }
    // add action
    NSString *action = [signDictionary valueForKey:@"action"];
    if (action) {
        [sigString appendString:[NSString stringWithFormat:@"|action=%@", action]];
    }
    // add count
    NSString *count = [signDictionary valueForKey:@"count"];
    if (count) {
        [sigString appendString:[NSString stringWithFormat:@"|count=%@", count]];
    }
    // add distance
    NSString *distance = [signDictionary valueForKey:@"distance"];
    if (distance) {
        [sigString appendString:[NSString stringWithFormat:@"|distance=%@", distance]];
    }
    // add facebook_places_id
    NSString *facebook_places_id = [signDictionary valueForKey:@"facebook_places_id"];
    if (facebook_places_id) {
        [sigString appendString:[NSString stringWithFormat:@"|facebook_places_id=%@", facebook_places_id]];
    }
    // add foursquare_id
    NSString *foursquare_id = [signDictionary valueForKey:@"foursquare_id"];
    if (foursquare_id) {
        [sigString appendString:[NSString stringWithFormat:@"|foursquare_id=%@", foursquare_id]];
    }
    // add foursquare_v2_id
    NSString *foursquare_v2_id = [signDictionary valueForKey:@"foursquare_v2_id"];
    if (foursquare_v2_id) {
        [sigString appendString:[NSString stringWithFormat:@"|foursquare_v2_id=%@", foursquare_v2_id]];
    }
    // add lat
    NSString *lat = [signDictionary valueForKey:@"lat"];
    if (lat) {
        [sigString appendString:[NSString stringWithFormat:@"|lat=%@", lat]];
    }
    // add lng
    NSString *lng = [signDictionary valueForKey:@"lng"];
    if (lng) {
        [sigString appendString:[NSString stringWithFormat:@"|lng=%@", lng]];
    }
    // add max_id
    NSString *max_id = [signDictionary valueForKey:@"max_id"];
    if (max_id) {
        [sigString appendString:[NSString stringWithFormat:@"|max_id=%@", max_id]];
    }
    // add max_like_id
    NSString *max_like_id = [signDictionary valueForKey:@"max_like_id"];
    if (max_like_id) {
        [sigString appendString:[NSString stringWithFormat:@"|max_like_id=%@", max_like_id]];
    }
    // add max_tag_id
    NSString *max_tag_id = [signDictionary valueForKey:@"max_tag_id"];
    if (max_tag_id) {
        [sigString appendString:[NSString stringWithFormat:@"|max_tag_id=%@", max_tag_id]];
    }
    // add max_timestamp
    NSString *max_timestamp = [signDictionary valueForKey:@"max_timestamp"];
    if (max_timestamp) {
        [sigString appendString:[NSString stringWithFormat:@"|max_timestamp=%@", max_timestamp]];
    }
    // add min_id
    NSString *min_id = [signDictionary valueForKey:@"min_id"];
    if (min_id) {
        [sigString appendString:[NSString stringWithFormat:@"|min_id=%@", min_id]];
    }
    // add min_tag_id
    NSString *min_tag_id = [signDictionary valueForKey:@"min_tag_id"];
    if (min_tag_id) {
        [sigString appendString:[NSString stringWithFormat:@"|min_tag_id=%@", min_tag_id]];
    }
    // add min_timestamp
    NSString *min_timestamp = [signDictionary valueForKey:@"min_timestamp"];
    if (min_timestamp) {
        [sigString appendString:[NSString stringWithFormat:@"|min_timestamp=%@", min_timestamp]];
    }
    // add q
    NSString *q = [signDictionary valueForKey:@"q"];
    if (q) {
        [sigString appendString:[NSString stringWithFormat:@"|q=%@", q]];
    }
    
    NSString *sec = @"3dde97c7a03d47eba2bbd521b1cd36a2";
    NSString *fuckStr = [sigString SHA256HMACWithKey:sec];
    return fuckStr;
} // signRequest


@end

Вызов метода

NSDictionary* URLParameters = @{@"endpoint":@"/tags/fashion/media/recent",
                                @"access_token":@"364765806.9b6a283.348582a9cb2348c6a43a18211777f098",
                                @"count": @"100",
                                };

NSLog(@"%@", [[SignRequest sharedRequest] signRequest:URLParameters]);

// Данный класс возвращает SIG-подпись в виде строки!!!