Translucent UINavigationBar cannot extend to top of screen - ios

Question

I want to make a reddish translucent UINavigationBar (for iOS9), and I found that the following codes are essential:
navController.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: .Default)
navController.navigationBar.shadowImage = UIImage()
navController.navigationBar.backgroundColor = UIColor(red: 1.0,green: 0.3,blue: 0.3,alpha: 0.9)
navController.navigationBar.translucent = true
It works fine if I simply created a UINavigationBar (instead of creating a UINavigationController), but it looks like this as I created a UINavigationController.
enter image description here
I found the culprit to be the line navController.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: .Default)
, but if I remove it, the bar looks like this:
enter image description here
So how can I solve this problem? (I'm creating the UINavigationController programmatically and sorry for the inconvenience that I cannot imbed images)

Answer 1

Edit:
You need to subclass the UINavigationBar in order to get the translucent background of desired color. Have a look at this answer:
https://stackoverflow.com/a/19043174/2082569
Adding necessary code here too for reference:
#interface UnderlayNavigationBar : UINavigationBar
#end
#interface UnderlayNavigationBar ()
{
UIView* _underlayView;
}
- (UIView*) underlayView;
#end
.
#implementation UnderlayNavigationBar
- (void) didAddSubview:(UIView *)subview
{
[super didAddSubview:subview];
if(subview != _underlayView)
{
UIView* underlayView = self.underlayView;
[underlayView removeFromSuperview];
[self insertSubview:underlayView atIndex:1];
}
}
- (UIView*) underlayView
{
if(_underlayView == nil)
{
const CGFloat statusBarHeight = 20; // Make this dynamic in your own code...
const CGSize selfSize = self.frame.size;
_underlayView = [[UIView alloc] initWithFrame:CGRectMake(0, -statusBarHeight, selfSize.width, selfSize.height + statusBarHeight)];
[_underlayView setAutoresizingMask:(UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight)];
[_underlayView setBackgroundColor:[UIColor colorWithRed:1.0f green:0.3f blue:0.3f alpha:1.0f]];
[_underlayView setAlpha:0.7f];
[_underlayView setUserInteractionEnabled:NO];
}
return _underlayView;
}
#end
.
UIViewController* rootViewController = ...;
UINavigationController* navigationController = [[UINavigationController alloc] initWithNavigationBarClass:[UnderlayNavigationBar class] toolbarClass:nil];
[navigationController setViewControllers:#[rootViewController]];