I want to set field level security for particular field of object from Apex.
e.g  There is custom field named  "SLASerialNumber__c"  on Account object and I have System Administrator Profile.
So I want to give Read and Edit Access of  field to Profile.

How it's possible?

I have written apex class like this.
try 
        {
            String userId = UserInfo.getUserId();
            User userRecord = [SELECT Id, Name FROM User WHERE Id = : userId];
            String userName = userRecord.Name;
            String ttsDialog = dialog;
            Id requestId = reqId;
            String sObjName = requestId.getSObjectType().getDescribe().getName();
            
            List<tts__Message__b> ttsMessageList = new List<tts__Message__b> ();
            
            tts__Message__b ttsMessageObj = new tts__Message__b();
            ttsMessageObj.tts__To__c = toReceivers;
            ttsMessageObj.tts__From__c = fromSender;
            ttsMessageObj.tts__CreatedBy__c = userName;
            ttsMessageObj.tts__CreatedDate__c = System.now();
            ttsMessageObj.tts__Message_Body__c = ttsDialog;
            ttsMessageObj.tts__Message_ID__c = Utilities.GenerateGUID();
            ttsMessageObj.tts__ParentId__c = requestId;
            ttsMessageObj.tts__ParentObjectAPIName__c = sObjName;
            ttsMessageObj.tts__Message_Direction__c = chatType;
            ttsMessageList.add(ttsMessageObj);
            
            database.insertImmediate(ttsMessageList);
            
            
            
        }catch (Exception e) {
            system.debug('@@Exception in the insertBigObjectDialog method::'+e);
        }

I want to set field level security for particular field of object from Apex.
e.g  There is custom field named  "SLASerialNumber__c"  on Account object and I have System Administrator Profile.
So I want to give Read and Edit Access of  field to Profile.

How it's possible?

I have written apex class like this.
try 
        {
            String userId = UserInfo.getUserId();
            User userRecord = [SELECT Id, Name FROM User WHERE Id = : userId];
            String userName = userRecord.Name;
            String ttsDialog = dialog;
            Id requestId = reqId;
            String sObjName = requestId.getSObjectType().getDescribe().getName();
            
            List<tts__Message__b> ttsMessageList = new List<tts__Message__b> ();
            
            tts__Message__b ttsMessageObj = new tts__Message__b();
            ttsMessageObj.tts__To__c = toReceivers;
            ttsMessageObj.tts__From__c = fromSender;
            ttsMessageObj.tts__CreatedBy__c = userName;
            ttsMessageObj.tts__CreatedDate__c = System.now();
            ttsMessageObj.tts__Message_Body__c = ttsDialog;
            ttsMessageObj.tts__Message_ID__c = Utilities.GenerateGUID();
            ttsMessageObj.tts__ParentId__c = requestId;
            ttsMessageObj.tts__ParentObjectAPIName__c = sObjName;
            ttsMessageObj.tts__Message_Direction__c = chatType;
            ttsMessageList.add(ttsMessageObj);
            
            database.insertImmediate(ttsMessageList);
            
            
            
        }catch (Exception e) {
            system.debug('@@Exception in the insertBigObjectDialog method::'+e);
        }