Resolve "12-log-in-out-navbar"

Closes #12 (closed) Added in login/out functionality to navbar. Icon and name of the login tab in navbar will now change depending on whether variable 'isLoggedIn'is toggled

navigation/MainContainer.tsx

 import * as React from 'react';
-import {Text, View} from 'react-native';
 
 import { NavigationContainer } from '@react-navigation/native';
 import { createBottomTabNavigator } from '@react-navigation/bottom-tabs';
@@ -13,17 +12,19 @@ import useInfoStore from '../store/InfoStorage';
 
 // names of screens
 const homeName = 'Home'
-const loginName = 'Login'
+// Making loginName a variable so that it can be changed to 'Log out' if user is logged in
+let loginName = 'Login'
 const profileName = 'Profile'
 
 const Navbar = createBottomTabNavigator();
 
 
-
-
-
 export default function MainContainer(){
     const isLoggedIn = useInfoStore((state)=>state.isLoggedIn);
+    if (isLoggedIn){
+        loginName = 'Log out';
+    }
+
     return(
         <NavigationContainer>
             <Navbar.Navigator
@@ -31,8 +32,17 @@ export default function MainContainer(){
                 screenOptions={({route}) => ({
                     tabBarIcon: ({focused, color, size}) => {
                         let iconName;
-                        if (isLoggedIn == false){
+                        if(isLoggedIn == true){
                         
+                        
+                            if(route.name === loginName){
+                                iconName = focused ? 'ios-log-out' : 'ios-log-out-outline';
+                            } else if(route.name === homeName){
+                                iconName = focused ? 'home' : 'home-outline';
+                            } else if(route.name === profileName){
+                                iconName = focused ? 'person' : 'person-outline';    
+                            }
+                        } else {
                             if(route.name === loginName){
                                 iconName = focused ? 'ios-log-in' : 'ios-log-in-outline';
                             } else if(route.name === homeName){
@@ -42,25 +52,16 @@ export default function MainContainer(){
                             }
                         }
                         
-                    
-                    
                         return <IonIcons name={iconName} size={size} color={color} />
                         
                     },
                     tabBarStyle: {
                         backgroundColor: '#3b3b3b',
                         height: 60,
-                    
                     },
                     tabBarLabelStyle: { fontSize: 12},
                     tabBarActiveTintColor: 'tomato',
-
-                })}
-          
-                
-                
-                
-                >
+                })}>
                 <Navbar.Screen name={homeName} component={HomeScreen} />
                 <Navbar.Screen name={loginName} component={LoginScreen} />
                 <Navbar.Screen name={profileName} component={ProfileScreen} />
@@ -68,8 +69,5 @@ export default function MainContainer(){
             </Navbar.Navigator>
         </NavigationContainer>
 
-                
-
-
     )
-}
\ No newline at end of file
+}