navigation menu not at full width of screen - objective-c

Question

I'm writing an app in objective C for ios 8, and my navigation bar has an annoying margin thats causing it to be shifted to the right ~20 pixels for leftBarButtonItem and ~20 left for rightBarButtonItem, as shown in the image below. I have tried using negative spacers per some other posts to no avail. Any ideas?
(I'm trying to do this without using storyboards or xibs.)
Here is the code:
UIToolbar* toolbar_temp = [[UIToolbar alloc] init];
toolbar_temp.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 45);
toolbar_temp.barTintColor= [UIColor blackColor];
NSMutableArray *items = [[NSMutableArray alloc] init];
UIBarButtonItem *spaceItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
UIImage *camimage = [UIImage imageNamed:#"cancel"];
UIBarButtonItem *customItem = [[UIBarButtonItem alloc] initWithImage:camimage style:UIBarButtonItemStylePlain target:self action:nil];
[items addObject:spaceItem ];
[items addObject:customItem ];
[items addObject:spaceItem ];
[toolbar_temp setItems:items animated:NO];
UIBarButtonItem *allButton = [[UIBarButtonItem alloc] initWithCustomView:toolbar_temp];
self.navigationItem.leftBarButtonItem = allButton;
EDIT:
I'm not sure if this gives any hints, but for some reason this works:
[[UINavigationBar appearance] setBarStyle:UIBarStyleBlackTranslucent];
While this does not:
[self.navigationController.navigationBar setBarStyle:UIBarStyleBlackTranslucent];
SOLUTION:
I ended up finding the solution myself. The issue was that I have a tabbar controller which had a navigation controller as one of the views. The navigation controller can only be setup in viewDidload, which doesn't get called in tabbar controllers. The solution was to add viewDidAppear and add the navigation controller within that function.
- (void)viewDidAppear:(BOOL)animated{[self addToolbar];}
Thanks all for the help!

Answer 1

It seems you cannot alter the minimum margins. You can do is add the toolbar_temp to the navigation bar:
[self.navigationController.navigationBar addSubview:toolbar_temp];
Or add to the self.view:
self.navigationController.navigationBarHidden = YES;
[self.view addSubview:toolbar_temp];