UIBarButtonItem doesn't appear - ios

Question

I have an issue, when the view is loaded, it will load the UIBarButtonItem, but then i have to set it to nil in "mostra_filtro_btn", but then again in "load_map" i have to set it, but it doesn't show up.
Here is my code:
//
// FirstViewController.m
// House Finder
//
// Created by Giovanni Poli on 12/05/15.
// Copyright (c) 2015 Giovanni Poli. All rights reserved.
//
#import "MapViewController.h"
#import <QuartzCore/QuartzCore.h>
#import "Reachability.h"
#import "UIKit/UIKit.h"
#import <Foundation/Foundation.h>
#import "FiltroViewController.h"
#interface MapViewController ()
#end
#implementation MapViewController
#synthesize filtro_controller,overlay_filtro_counter,mappa_controller;
-(void)load_map{
NSLog(#"load_map");
[mapView removeFromSuperview];
[mappa_controller.view removeFromSuperview];
[filtro_controller.view removeFromSuperview];
UIBarButtonItem *Button = [[UIBarButtonItem alloc] initWithTitle:#"Filtro" style:UIBarButtonItemStyleBordered target:self action:#selector(mostra_filtro_btn:)];
[Button setTitle:#"Filtro"];
[Button setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor whiteColor], NSForegroundColorAttributeName,nil]forState:UIControlStateNormal];
self.navigationItem.rightBarButtonItem = Button;
}
- (id) init{
filtro_controller = [[FiltroViewController alloc]init];
[self.view addSubview:filtro_controller.view];
[self addChildViewController:filtro_controller];
return self;
}
- (void)viewDidLoad {
self.title = #"Mappa";
self.navigationItem.title = #"House Finder";
self.navigationController.navigationBar.translucent = FALSE;
UIBarButtonItem *Button = [[UIBarButtonItem alloc] initWithTitle:#"Filtro" style:UIBarButtonItemStyleBordered target:self action:#selector(mostra_filtro_btn:)];
[Button setTitle:#"Filtro"];
[Button setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor whiteColor], NSForegroundColorAttributeName,nil]forState:UIControlStateNormal];
self.navigationItem.rightBarButtonItem = Button;
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"data" ofType:#"json"];
NSData *content = [[NSData alloc] initWithContentsOfFile:filePath];
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:content options:kNilOptions error:nil];
NSArray * json_all = [json objectForKey:#"results"];
mapView = [[MKMapView alloc]initWithFrame:CGRectMake(0,0,self.view.frame.size.width,self.view.frame.size.height-40)];
mapView.delegate = self;
mapView.showsUserLocation = NO;
mapView.userInteractionEnabled = YES;
CLLocationCoordinate2D annotationCoord;
self.view.userInteractionEnabled = YES;
NSDictionary * temp;
for (id object in json_all) {
temp = object[#"titolo"];
annotationCoord.latitude = [object[#"lat"] floatValue];
annotationCoord.longitude = [object[#"lon"] floatValue];
MKPointAnnotation *annotationPoint = [[MKPointAnnotation alloc] init];
annotationPoint.coordinate = annotationCoord;
annotationPoint.title = object[#"titolo"];
annotationPoint.subtitle = object[#"agenzia"];
[mapView addAnnotation:annotationPoint];
}
[mapView showAnnotations:[mapView annotations] animated:YES];
[self.view addSubview:mapView];
[self.view setNeedsDisplay];
}
- (IBAction) mostra_filtro_btn: (id)sender{
NSLog(#"mostra_filtro_btn");
self.navigationItem.rightBarButtonItem = nil;
filtro_controller = [[FiltroViewController alloc]init];
[self.view addSubview:filtro_controller.view];
[self addChildViewController:filtro_controller];
}
- (MKAnnotationView *)mapView:(MKMapView *)mapViews viewForAnnotation:annotation{
if (annotation == mapViews.userLocation) return nil;
MKPointAnnotation * temp = annotation;
MKAnnotationView * m = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:#"casa"];
m.canShowCallout = YES;
m.enabled = YES;
m.userInteractionEnabled = YES;
NSString * icon_file = [NSString stringWithFormat:#"%#.png",temp.subtitle];
m.image = [UIImage imageNamed:icon_file];
return m;
}
- (void)mapView:(MKMapView *)mapView didSelectAnnotationView:(MKAnnotationView *)view{
NSLog(#"overlay prezzo");
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
#end

Answer 1

Use the following code to nil the navigation item so it will hide where ever you want
[self.navItem setRightBarButtonItem:nil];
[self.navItem setLeftBarButtonItem:nil];

Answer 2

Try first create the UIButton then put it into the navigation button as follow
UIButton *backButton = [[UIButton alloc] initWithFrame: CGRectMake(0, 0, 44.0f, 30.0f)];
[backButton setImage:[UIImage imageNamed:#"back.png"] forState:UIControlStateNormal];
[backButton addTarget:self action:#selector(popVC) forControlEvents:UIControlEventTouchUpInside];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];

Answer 3

Since I can't post this as a comment here is what I think is missing inside load_map:
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(#"load_map");
[mapView removeFromSuperview];
[mappa_controller.view removeFromSuperview];
[filtro_controller.view removeFromSuperview];
UIBarButtonItem *Button = [[UIBarButtonItem alloc] initWithTitle:#"Filtro" style:UIBarButtonItemStyleBordered target:self action:#selector(mostra_filtro_btn:)];
[Button setTitle:#"Filtro"];
[Button setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor whiteColor], NSForegroundColorAttributeName,nil]forState:UIControlStateNormal];
self.navigationItem.rightBarButtonItem = Button;
})
This is a possible solution till you try it. If you share the code from where you call load_map it would be great!
Cheers!

Answer 4

Your code works perfect, as you said you are adding button with method mostra_filtro_btn : in viewDidLoad method, and on click of button, button from navigation bar set to nil.
But the problem is that, from nowhere you calls load_map method. You need to call this method once the button gets nil, to get it back with load_map method.
May you get it.
Enjoy Coding!!