Hide navigation bar without moving scrollView - ios

Question

I have a viewController where am showing image for adding the zooming functionality I added the scrollView in viewController and inside of ScrollView I added ImageView everything is working fine expect of one thing, am hiding, and showing the bars (navigation bar + tab bar) on tap but when hiding them my imageView moves upside see the below images
See here's the image and the bars.
Here I just tapped on the view and bars got hidden but as you can see my imageView is also moved from its previous place, this is what I want to solve I don't want to move my imageView.
This is how am hiding my navigation bar:
func tabBarIsVisible() ->Bool {
return self.tabBarController?.tabBar.frame.origin.y < CGRectGetMaxY(self.view.frame)
}
func toggle(sender: AnyObject) {
navigationController?.setNavigationBarHidden(navigationController?.navigationBarHidden == false, animated: true)
setTabBarVisible(!tabBarIsVisible(), animated: true)
}
any idea how can I hide and show the bars without affecting my other Views?

Answer 1

The problem is that you need to set the constraint of your imageView to your superView, not TopLayoutGuide or BottomLayoutGuide.
like so:
Then you can do something like this to make the it smootly with animation:
import UIKit
class ViewController: UIViewController {
#IBOutlet var imageView: UIImageView!
var barIsHidden = false
var navigationBarHeight: CGFloat = 0
var tabBarHeight: CGFloat = 0
override func viewDidLoad() {
super.viewDidLoad()
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(ViewController.hideAndShowBar))
view.addGestureRecognizer(tapGesture)
navigationBarHeight = (self.navigationController?.navigationBar.frame.size.height)!
tabBarHeight = (self.tabBarController?.tabBar.frame.size.height)!
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func hideAndShowBar() {
print("tap!!")
if barIsHidden == false {
UIView.animateWithDuration(0.5, delay: 0.0, options: .CurveEaseOut, animations: {
// fade animation
self.navigationController?.navigationBar.alpha = 0.0
self.tabBarController?.tabBar.alpha = 0.0
// set height animation
self.navigationController?.navigationBar.frame.size.height = 0.0
self.tabBarController?.tabBar.frame.size.height = 0.0
}, completion: { (_) in
self.barIsHidden = true
})
} else {
UIView.animateWithDuration(0.5, delay: 0.0, options: .CurveEaseOut, animations: {
// fade animation
self.navigationController?.navigationBar.alpha = 1.0
self.tabBarController?.tabBar.alpha = 1.0
// set height animation
self.navigationController?.navigationBar.frame.size.height = self.navigationBarHeight
self.tabBarController?.tabBar.frame.size.height = self.tabBarHeight
}, completion: { (_) in
self.barIsHidden = false
})
}
}
}
Here is the result:
I have created an example project for you at: https://github.com/khuong291/Swift_Example_Series
You can see it at project 37
Hope this will help you.