Offline map tiles have stopped displaying - ios

Question

I have downloaded tiles for a small town in zooms 15 to 18. They were displaying as expected but now don't.
I was using xcode 7 with swift 2 on Yosemite. I'm now with xcode 8.1 with swift 3 on sierra. I'm pretty sure the problem started before the upgrade, but have no time machine to go back. I upgraded because I wanted to test the app on my IPad 2, got the message that xcode wasn't compatible with the ios on the ipad, then got a message that xcode 8.1 cant be loaded to Yosemite hence upgrade to sierra.
The code is below. And the console output bellow that. No error given
//
// MapViewController.swift
// button scale
//
// Created by Colin McGarry on 24/03/16.
// Copyright © 2016 Colin McGarry. All rights reserved.
//
import UIKit
import MapKit
import CoreLocation
class MapViewController: UIViewController /*, MKMapViewDelegate*/{
var guideData: GuideData?
var dataM:[GuideData] = [GuideData]()
var placeNumb = 0
var modifyingMap = true
#IBOutlet weak var mapView: MKMapView!
override func viewDidLoad() {
super.viewDidLoad()
let IS_RETINA = (UIScreen.mainScreen().respondsToSelector(#selector(UIScreen.displayLinkWithTarget(_:selector:))) && (UIScreen.mainScreen().scale >= 2.0))
// from shankar map
if IS_RETINA {
print("Is Retina")
} else {
print("not retina")
}
zoomToRegion()
let annotations = getMapAnnotations()
// Add mappoints to Map
mapView.addAnnotations(annotations)
// end shankar map
//Get the URL template to the map tiles
let baseURL = NSBundle.mainBundle().bundleURL.absoluteString
let urlTemplate = baseURL!.stringByAppendingString("osmm/{z}/{x}/{y}.png/")
//let urlTemplate = baseURL.stringByAppendingString("two/{z}/{x}/{y}#2x.png/")
//let urlTemplate = "http://tile.openstreetmap.org/{z}/{x}/{y}.png"
print(urlTemplate)
let carte_indice = MKTileOverlay(URLTemplate:urlTemplate)
carte_indice.geometryFlipped = false
carte_indice.canReplaceMapContent = true
//carte_indice.tileSize = CGSize(width: 512, height: 512)
carte_indice.maximumZ = 16
carte_indice.minimumZ = 18
self.mapView.addOverlay(carte_indice)
}
/// from shankar map
func zoomToRegion() {
let location = CLLocationCoordinate2D(latitude: 49.275, longitude: -0.7028)
let region = MKCoordinateRegionMakeWithDistance(location, 500.0, 500.0)
mapView.setRegion(region, animated: true)
}
//MARK:- Annotations
func getMapAnnotations() -> [Stands] {
var annotations:Array = [Stands]()
//load plist file
var stands: NSArray?
if let path = NSBundle.mainBundle().pathForResource("stands", ofType: "plist") {
stands = NSArray(contentsOfFile: path)
}
//iterate and create annotations
if let items = stands {
for item in items {
let lat = item.valueForKey("lat") as! Double
let long = item.valueForKey("long")as! Double
let annotation = Stands(latitude: lat, longitude: long)
let tit = item.valueForKey("title") as! String
let numb = item.valueForKey("no") as! Int
annotation.title = "\(numb) \(tit)"
annotation.no = numb
// new added
// annotation.enabled = true
// annotation.canShowCallOut = true
// end added
annotations.append(annotation)
}
}
return annotations
}
// end From Shankar map
func mapView(mapView: MKMapView!, viewForAnnotation annotation: MKAnnotation!) -> MKAnnotationView! {
// 1
let identifier = "Stand"
// 2
if annotation.isKindOfClass(Stands.self) {
// 3
var annotationView = mapView.dequeueReusableAnnotationViewWithIdentifier(identifier)
if annotationView == nil {
//4
annotationView = MKPinAnnotationView(annotation:annotation, reuseIdentifier:identifier)
annotationView!.canShowCallout = true
// 5
let btn = UIButton(type: .DetailDisclosure)
annotationView!.rightCalloutAccessoryView = btn
} else {
// 6
annotationView!.annotation = annotation
}
return annotationView
}
// 7
return nil
}
func mapView( mapView: MKMapView!, annotationView view: MKAnnotationView!, calloutAccessoryControlTapped control: UIControl!) {
let standM = view.annotation as! Stands
let placeName = standM.title
let placeInfo = standM.title
placeNumb = standM.no!
/*
let ac = UIAlertController(title: placeName, message: placeInfo, preferredStyle: .Alert)
ac.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
presentViewController(ac, animated: true, completion: nil) */
performSegueWithIdentifier("MapToText", sender: self)
}
func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
// enforce maximum zoom level
let place = mapView.visibleMapRect
if( place.origin.x < 133686298
|| place.origin.x > 133697376
|| place.origin.y < 91864219
|| place.origin.y > 91874305
)
{
zoomToRegion()
}
print("alt \(mapView.camera.altitude)")
let maxAlt = 3000.00
if (mapView.camera.altitude > maxAlt && self.modifyingMap)
{
self.modifyingMap = false
// prevents strange infinite loop case
self.mapView.zoomEnabled = false
/* self.mapView.scrollEnabled = false
self.mapView.userInteractionEnabled = false
*/
print("place \(place)")
self.mapView.camera.altitude = maxAlt
self.modifyingMap = true
print("alt>\(maxAlt)")
} else {
self.mapView.zoomEnabled = true
print("place2 \(place)")
print("x \(place.origin.x)")
print(" alt less than \(maxAlt)")
print(mapView.camera.altitude)
}
}
func mapView(mapView: MKMapView!, rendererForOverlay overlay: MKOverlay!) -> MKOverlayRenderer!
{
print("call overlay")
if overlay is MKTileOverlay
{
print("is MKTileoverlay")
let renderer = MKTileOverlayRenderer(overlay:overlay)
renderer.alpha = 0.8
return renderer
}
return nil
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "MapToText" {
let webviewController:webViewController = segue.destinationViewController as! webViewController
webviewController.index = placeNumb - 1
// webviewController.standTitle = sender as! MKAnnotationView
webviewController.inde = placeNumb - 1
print("prepSeg \(webviewController.inde)")
}
}
}
console output
/Users/colinmcgarry/Library/Developer/CoreSimulator/Devices/4F5E35FC-45F9-4A16-8A0A-1AFD51616CCA/data/Containers/Bundle/Application/046B53E5-D3CD-4E7A-926D-7D77E069AAA0/button scale.app/stands.plist
Optional("/Users/colinmcgarry/Library/Developer/CoreSimulator/Devices/4F5E35FC-45F9-4A16-8A0A-1AFD51616CCA/data/Containers/Bundle/Application/046B53E5-D3CD-4E7A-926D-7D77E069AAA0/button scale.app/2page.html")
Is Retina
alt 1100.94691259802
place2 MKMapRect(origin: __C.MKMapPoint(x: 133691120.58898854, y: 91870217.34526816), size: __C.MKMapSize(width: 5123.4971518665552, height: 6063.3100336045027))
x 133691120.588989
alt less than 3000.0
1100.94691259802
file:///Users/colinmcgarry/Library/Developer/CoreSimulator/Devices/4F5E35FC-45F9-4A16-8A0A-1AFD51616CCA/data/Containers/Bundle/Application/046B53E5-D3CD-4E7A-926D-7D77E069AAA0/button%20scale.app/osmm/{z}/{x}/{y}.png/
call overlay
is MKTileoverlay

Answer 1

I found the problem. But it's not in the code I included.
I had put min and max zoom. When I changed the values I interchanged min and max
overlay.maximumZ = 15
overlay.minimumZ = 17
These conditions are mutually contradicting so overlay didn't show.
if I'd written min above max I might have noticed before.