AMPNavigationBar.m

// .h

@interface AMPNavigationBar : UINavigationBar

@end

// .m

@interface AMPNavigationBar ()

@property (nonatomic, strong) CALayer *extraColorLayer;

@end

static CGFloat const kDefaultColorLayerOpacity = 0.5f;
static CGFloat const kSpaceToCoverStatusBars = 100.0f;

@implementation AMPNavigationBar

- (void)setBarTintColor:(UIColor *)barTintColor
{
  [super setBarTintColor:barTintColor];
  if (self.extraColorLayer == nil) {
    self.extraColorLayer = [CALayer layer];
    self.extraColorLayer.opacity = kDefaultColorLayerOpacity;
    [self.layer addSublayer:self.extraColorLayer];
  }
  self.extraColorLayer.backgroundColor = barTintColor.CGColor;
}

- (void)layoutSubviews
{
  [super layoutSubviews];
  if (self.extraColorLayer != nil) {
    self.extraColorLayer.frame = CGRectMake(0, 0 - kSpaceToCoverStatusBars, CGRectGetWidth(self.bounds), CGRectGetHeight(self.bounds) + kSpaceToCoverStatusBars);
  }
}

@end

// the easy way to use it is to subclass UINavigationController and override:
- (id)initWithRootViewController:(UIViewController *)rootViewController
{
  self = [super initWithNavigationBarClass:[APNavigationBar class] toolbarClass:[UIToolbar class]];
  if (self) {
    self.viewControllers = @[ rootViewController ];
  }
  return self;
}