use like this.....

    Create file

    #import <Foundation/Foundation.h>`    
    #import "SharedManager.h"
    #import "Constant.h"
    #import "UserDetails.h"

    @interface APISession : NSURLSession<NSURLSessionDelegate>
    @property (nonatomic, retain) NSMutableData *responseData;
    +(void)postRequetsWithParam:(NSMutableDictionary* )objDic withAPIName:(NSString*
    )strAPIURL completionHandler:(void (^)(id result, BOOL status))completionHandler;
    @end

****************.m*************************
    #import "APISession.h"
    #import <UIKit/UIKit.h>
    @implementation APISession

    +(void)postRequetsWithParam:(NSMutableDictionary *)objDic withAPIName:(NSString
    *)strAPIURL completionHandler:(void (^)(id, BOOL))completionHandler
    {
    NSURL *url=[NSURL URLWithString:strAPIURL];
    NSMutableURLRequest *request=[[NSMutableURLRequest alloc]initWithURL:url];
    [request setHTTPMethod:@"POST"];
    [request addValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    NSError *err = nil;

    NSData *data=[NSJSONSerialization dataWithJSONObject:objDic options:NSJSONWritingPrettyPrinted error:&err];
    [request setHTTPBody:data];

    NSString *strJsonFormat = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"API URL: %@ \t  Api Request Parameter ::::::::::::::%@",url,strJsonFormat);
    //    NSLog(@"Request data===%@",objDic);
    NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
    NSURLSession *session = [NSURLSession sessionWithConfiguration: defaultConfigObject delegate: nil delegateQueue: [NSOperationQueue mainQueue]];

    //  NSURLSession *session=[NSURLSession sharedSession];

    NSURLSessionTask *task=[session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error)
                            {
                                if (error==nil) {
                                    NSDictionary *dicData=[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];\
                                    NSLog(@"Response Data=============%@",dicData);
                                    if([[dicData valueForKey:@"tokenExpired"]integerValue] == 1)
                                    {

                                        NSLog(@"hello");
                                        NSDictionary *dict = [NSDictionary dictionaryWithObject:@"Access Token Expire." forKey:@"message"];
                                        [[NSNotificationCenter defaultCenter] postNotificationName:@"UserLogOut" object:self userInfo:dict];
                                    }
                                    dispatch_async(dispatch_get_main_queue(), ^{
                                        completionHandler(dicData,(error == nil));
                                    });
                                    NSLog(@"%@",dicData);
                                }
                                else{
                                    dispatch_async(dispatch_get_main_queue(), ^{
                                        completionHandler(error.localizedDescription,NO);
                                    });
                                }
                            }];
    //    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
    [task resume];
    //    });
    }
    @end

    *****************************in .your view controller***********
    #import "file"
    txtEmail.text = [txtEmail.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

    {
            [SVProgressHUD showWithStatus:@"Loading..."];
            [SVProgressHUD setDefaultMaskType:SVProgressHUDMaskTypeGradient];

            NSMutableDictionary *objLoginDic=[[NSMutableDictionary alloc] init];
            [objLoginDic setValue:txtEmail.text forKey:@"email"];
            [objLoginDic setValue:@0            forKey:kDeviceType];
            [objLoginDic setValue:txtPassword.text forKey:kPassword];
            [objLoginDic setValue:@"376545432"  forKey:kDeviceTokan];
            [objLoginDic setValue:@""           forKey:kcountryId];
            [objLoginDic setValue:@""           forKey:kfbAccessToken];
            [objLoginDic setValue:@0            forKey:kloginType];

            [APISession postRequetsWithParam:objLoginDic withAPIName:KLOGIN_URL completionHandler:^(id result, BOOL status) {

                [SVProgressHUD dismiss];

                NSInteger statusResponse=[[result valueForKey:kStatus] integerValue];
                NSString *strMessage=[result valueForKey:KMessage];
                if (status) {
                    if (statusResponse == 1)
                {
                        UserDetails *objLoginUserDetail=[[UserDetails alloc]
                        initWithObject:[result valueForKey:@"userDetails"]];
                          [[NSUserDefaults standardUserDefaults]
                        setObject:@(objLoginUserDetail.userId) forKey:@"user_id"];
                        [[NSUserDefaults standardUserDefaults] synchronize];
                        [self clearTextfeilds];
                        HomeScreen *obj=[Kiran_Storyboard instantiateViewControllerWithIdentifier:@"HomeScreen"];
                        [self.navigationController pushViewController:obj animated:YES];
                    }
                    else{
                        [strMessage showAsAlert:self];
                    }
                }
            }];
        }
**********use model class for represnt data*************

    #import <Foundation/Foundation.h>
    #import "Constant.h"
    #import <objc/runtime.h>


    @interface UserDetails : NSObject
    @property(strong,nonatomic) NSString *emailId,
    *deviceToken,
    *countryId,
    *fbAccessToken,
    *accessToken,
    *countryName,
    *isProfileSetup,
    *profilePic,
    *firstName,
    *lastName,
    *password;

    @property (assign) NSInteger userId,deviceType,loginType;

    -(id)initWithObject :(NSDictionary *)dicUserData;
    -(void)saveLoginUserDetail;
    +(UserDetails *)getLoginUserDetail;
    -(UserDetails *)getEmptyModel;
    - (NSArray *)allPropertyNames;
    -(void)printDescription;
       -(NSMutableDictionary *)getDictionary;

    @end

    ******************model.m*************

    #import "UserDetails.h"
    #import "SharedManager.h"

    @implementation UserDetails



      -(id)initWithObject :(NSDictionary *)dicUserData
       {
       self = [[UserDetails alloc] init];
       if (self)
       {
           @try {
               [self setFirstName:([dicUserData valueForKey:@"firstName"] != [NSNull null])?
               [dicUserData valueForKey:@"firstName"]:@""];


               [self setUserId:([dicUserData valueForKey:kUserId] != [NSNull null])?
               [[dicUserData valueForKey:kUserId] integerValue]:0];


               }
        @catch (NSException *exception) {
            NSLog(@"Exception: %@",exception.description);
        }
        @finally {
        }
    }
    return self;
}

    -(UserDetails *)getEmptyModel{
    [self setFirstName:@""];
    [self setLastName:@""];



    [self setDeviceType:0];


    return self;
       }

     -  (void)encodeWithCoder:(NSCoder *)encoder {
    //    Encode properties, other class variables, etc
    [encoder encodeObject:_firstName forKey:kFirstName];


    [encoder encodeObject:[NSNumber numberWithInteger:_deviceType] forKey:kDeviceType];

    }

    - (id)initWithCoder:(NSCoder *)decoder {
    if((self = [super init])) {
        _firstName = [decoder decodeObjectForKey:kEmailId];

        _deviceType= [[decoder decodeObjectForKey:kDeviceType] integerValue];

    }
    return self;
    }
    - (NSArray *)allPropertyNames
    {
    unsigned count;
    objc_property_t *properties = class_copyPropertyList([self class], &count);

    NSMutableArray *rv = [NSMutableArray array];

    unsigned i;
    for (i = 0; i < count; i++)
    {
        objc_property_t property = properties[i];
        NSString *name = [NSString stringWithUTF8String:property_getName(property)];
        [rv addObject:name];
    }

    free(properties);

    return rv;
    }

    -(void)printDescription{
    NSMutableDictionary *dic = [[NSMutableDictionary alloc] init];

    for(NSString *key in [self allPropertyNames])
    {
        [dic setValue:[self valueForKey:key] forKey:key];
    }
    NSLog(@"\n========================= User Detail ==============================\n");
    NSLog(@"%@",[dic description]);
    NSLog(@"\n=============================================================\n");
    }
    -(NSMutableDictionary *)getDictionary{
    NSMutableDictionary *dic = [[NSMutableDictionary alloc] init];
    for(NSString *key in [self allPropertyNames])
    {
        [dic setValue:[self valueForKey:key] forKey:key];
    }
    return dic;
    }
    #pragma mark
    #pragma mark - Save and get User details
    -(void)saveLoginUserDetail{
    NSData *encodedObject = [NSKeyedArchiver archivedDataWithRootObject:self];
    [Shared_UserDefault setObject:encodedObject forKey:kUserDefault_SavedUserDetail];
    [Shared_UserDefault synchronize];
    }
      +(UserDetails *)getLoginUserDetail{
      NSData *encodedObject = [Shared_UserDefault objectForKey:kUserDefault_SavedUserDetail];
    UserDetails *object = [NSKeyedUnarchiver unarchiveObjectWithData:encodedObject];
    return object;
   }
    @end


     ************************usefull code while add data into model and get data********

                   NSLog(@"Response %@",result);
                  NSString *strMessg = [result objectForKey:kMessage];
                 NSString *status = [NSString stringWithFormat:@"%@",[result
                objectForKey:kStatus]];

            if([status isEqualToString:@"1"])
            {
                arryBankList =[[NSMutableArray alloc]init];

                NSMutableArray *arrEvents=[result valueForKey:kbankList];
                ShareOBJ.isDefaultBank = [result valueForKey:kisDefaultBank];
                if ([arrEvents count]>0)
                {

                for (NSMutableArray *dic in arrEvents)
                    {
                        BankList *objBankListDetail =[[BankList alloc]initWithObject:[dic
                         mutableCopy]];
                        [arryBankList addObject:objBankListDetail];
                    }
           //display data using model...
           BankList *objBankListing  =[arryBankList objectAtIndex:indexPath.row];