unrecognized selector sent to instance for nsobject file

Here is my nsobject file
.h
#import <Foundation/Foundation.h>
@interface user : NSObject
@property(nonatomic,strong)NSString *userName,*userEmailId,familyId;
@property(assign)float latitude,longitude;
-(id)initWithUserName:(NSString
)un UserEmail:(NSString *)ue FamilyId:(NSString *)fi Latitude:(long)lat Longitude:(float)lon;
-(void)setUserName:(NSString *)userName1;
-(void)setUserEmailId:(NSString *)userEmailId1;
@end
.m
#import “user.h”
@implementation user
@synthesize userEmailId,userName,familyId,latitude,longitude;
-(id)initWithUserName:(NSString *)un UserEmail:(NSString *)ue FamilyId:(NSString *)fi Latitude:(long)lat Longitude:(float)lon
{
userName=un;
userEmailId=ue;
familyId=fi;
latitude=lat;
longitude=lon;
return self;
}
-(id)init
{
return self;
}
-(void)setUserName:(NSString *)userName1
{

if (!self.userName)
{
self.userName=userName1;
}

}
-(void)setUserEmailId:(NSString *)userEmailId1
{
self.userEmailId=userEmailId1;
}
@end
Now i want to update name whose emailid is "amit@gmail.com"
BackendlessDataQuery *query = [BackendlessDataQuery query];
query.whereClause = [NSString stringWithFormat:@"%@ = ‘%@’", @“userName”,@“amit@gmail.com”];
id<IDataStore> dataStore = [backendless.persistenceService of:[user class]];

//BackendlessCollection *collection =
[dataStore find:query response:^(BackendlessCollection * collection)
{
NSArray *a=[collection getCurrentPage];

int recordCount=[a count];

if (recordCount>0)
{

for(user *u in a)
{

Responder *responder = [Responder responder:self
selResponseHandler:@selector(responseHandler:)
selErrorHandler:@selector(errorHandler:)];
user *b=[user new];
b=u;
// [b setuserName:@""];
b.userName=@“am”;
[b setuserName:@“Amit”];
// b.userEmailId=self.emailId.text;
id<IDataStore> dataStore = [backendless.persistenceService of:[user class]];
[dataStore save:b responder:responder];

NSLog(@"%@",[b valueForKey:@“userEmailId”]);
}

[ProgressHUD showError:@“Emailid Already Present” Interaction:NO];

}
else
{

}

}
error:^(Fault *myfalult)
{

NSLog(@"%@",[myfalult description]);
}];

at line b.userName=@“am”; app is crashing saying
Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘-[__NSDictionaryM setuserName:]: unrecognized selector sent to instance 0x7b653450’

I have tried with setting setter method, changing property name’s cases but still app crashes

please help

Hello.
We are already looking into it.

Regards,
Ilya (VV)

You should update the latest Backendless SDK from CocoaPods (3.0.23 release) or from github (CommLibiOS and backendless with them include folders).