Reduced default minimum frame rate to 20 fps

CHANGELOG.md

@@ -5,6 +5,7 @@
 * It is now safe to set the `NavigationMapView.delegate` property of the `NavigationMapView` in `NavigationViewController.mapView`. Implement `MGLMapViewDelegate` in your own class to customize annotations and other details. ([#1601](https://github.com/mapbox/mapbox-navigation-ios/pull/1601))
 * Fixed an issue where the map view while navigating in CarPlay showed labels in the style’s original language instead of the local language. ([#1601](https://github.com/mapbox/mapbox-navigation-ios/pull/1601))
 * `NavigationMapViewDelegate.navigationMapView(_:routeStyleLayerWithIdentifier:source:)`, `NavigationMapViewDelegate.navigationMapView(_:routeCasingStyleLayerWithIdentifier:source:)`, `NavigationViewControllerDelegate.navigationViewController(_:routeStyleLayerWithIdentifier:source:)`, and `NavigationViewControllerDelegate.navigationViewController(_:routeCasingStyleLayerWithIdentifier:source:)` can now set the `MGLLineStyleLayer.lineGradient` property. ([#1799](https://github.com/mapbox/mapbox-navigation-ios/pull/1799))
+* Reduced the `NavigationMapView.minimumFramesPerSecond` property’s default value from 30 frames per second to 20 frames per second for improved performance on battery power. ([#1818](https://github.com/mapbox/mapbox-navigation-ios/pull/1818)) 
 
 ## v0.23.0 (October 24, 2018)
 * `CarPlayManager` is no longer a singleton; your application delegate is responsible for creating and owning an instance of this class. This fixes a crash in applications that specify the access token programmatically instead of in the Info.plist file. ([#1792](https://github.com/mapbox/mapbox-navigation-ios/pull/1792))

MapboxNavigation/NavigationMapView.swift

@@ -24,7 +24,7 @@ open class NavigationMapView: MGLMapView, UIGestureRecognizerDelegate {
      
      This property takes effect when the application has limited resources for animation, such as when the device is running on battery power. By default, this property is set to `MGLMapViewPreferredFramesPerSecond.lowPower`.
      */
-    @objc public var minimumFramesPerSecond = MGLMapViewPreferredFramesPerSecond.lowPower
+    @objc public var minimumFramesPerSecond = MGLMapViewPreferredFramesPerSecond(20)
 
     /**
      Returns the altitude that the map camera initally defaults to.