Showing user location when button on custom UITabBarController is pressed - ios

Question

I have a custom UITabBar controller, where I have buttons to switch between the view controllers. Here is an Image:
http://i.stack.imgur.com/UInLI.png
What I want to do it that when the main button is pressed the view will change to the mapViewController, and when it pressed again (on the same mapViewController) it will show to user Location.
I am using mapBox as my Map API, I have a function in my mapViewController,
findUserLocation()
and this show the user location by using:
mapView.userTrackingMode = MGLUserTrackingMode.Follow
So here is My code:
class CustomTabBarViewController: UITabBarController {
override func viewDidLoad() {
super.viewDidLoad()
self.tabBar.hidden = true
let tabBarView = CustomTabBarView()
tabBarView.viewdidload()
self.view.addSubview(tabBarView)
tabBarView.mapButton.addTarget(self, action: #selector(self.changeToMyMap), forControlEvents: UIControlEvents.TouchUpInside)
// Do any additional setup after loading the view.
}
func changeToMyMap(){
if (self.selectedIndex != 0){
self.selectedIndex = 0
}else{
let mapViewController = myMap() // the class Name
mapViewController.mapView.userTrackingMode = MGLUserTrackingMode.Follow
}
}
}
So when I pressed the button to show the user location I get an error. I think is because the Map is not loaded into the customTabViewController, but I have no Idea how to make it work.
when I try to call a function
from my customTabBarController, my application get a fatal error.
fatal error: unexpectedly found nil while unwrapping an Optional value

Answer 1

If you haven't used them already, these may be some helpful mapBox resources.
I'm not sure why it would be crashing with what you have there.
I would try putting some breakpoints in to find out where it's actually crashing.
Try putting one on the line if (self.selectedIndex != 0){
to see if it's actually going inside that method.
If it is, try typing po yourPropertyName i.e. po self.selectedIndex in the debug console to try and find out what property is returning nil.
Also, if you know what properties are optional, check where you're accessing them. That's where they could be nil.

Answer 2

In our Swift application, we made use of showsUserLocation to toggle the user location.
This would be worth trying, if you are simply trying to show the User Location.
The MGLUserTrackingMode in Mapbox iOS SDK 3.2.3 is for how to track the user location on the map (e.g., the experience when following a driving route).
How you could use showsUserLocation
func changeToMyMap(){
// not sure if the 'if/else' logic fit with what you intended, but
// left your code intact to better highlight how to use mapView.showsUserLocation
if (self.selectedIndex != 0){
self.selectedIndex = 0
mapViewController.mapView.showsUserLocation = false
}else{
let mapViewController = myMap()
// causes the map view to use the Core Location framework to find the current location
mapViewController.mapView.showsUserLocation = true
}
}
}
Be aware of this note in the docs for Mapbox iOS SDK 3.2.3. You will need to pay attention to set new keys in the .plist.
On iOS 8 and above, your app must specify a value for
NSLocationWhenInUseUsageDescription or NSLocationAlwaysUsageDescription in
its Info.plist to satisfy the requirements of the underlying Core Location
framework when enabling this property.
For comparison of how we use showsUserLocation in Mapbox (what produces the experience in the above GIF) —
#IBAction func handleSettings(sender: AnyObject) {
var trackingLocation = UIImage(named: "TrackingLocationOffMask.png")
switch (self.mapView.userLocationVisible) {
case true:
self.mapView.showsUserLocation = false
trackingLocation = UIImage(named: "TrackingLocationOffMask.png")
break
case false:
self.mapView.showsUserLocation = true
trackingLocation = UIImage(named: "TrackingLocationMask.png")
break
}
self.navigationItem.leftBarButtonItem?.image = trackingLocation
}