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#import "DDSLayerSelectionExample.h"
@import Mapbox;
NSString const *MBXExampleDDSLayerSelection = @"DDSLayerSelectionExample";
@interface DDSLayerSelectionExample () <MGLMapViewDelegate, UIGestureRecognizerDelegate>
@property (nonatomic) MGLMapView *mapView;
@end
@implementation DDSLayerSelectionExample
- (void)viewDidLoad {
[super viewDidLoad];
self.mapView = [[MGLMapView alloc] initWithFrame:self.view.bounds];
self.mapView.delegate = self;
[self.mapView setCenterCoordinate:CLLocationCoordinate2DMake(39.23225,-97.91015)];
self.mapView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
[self.view addSubview:self.mapView];
// Add a tap gesture recognizer to the map view.
UITapGestureRecognizer *gesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
gesture.delegate = self;
gesture.numberOfTapsRequired = 1;
[self.mapView addGestureRecognizer:gesture];
}
- (void)mapView:(MGLMapView *)mapView didFinishLoadingStyle:(MGLStyle *)style {
// Load a tileset containing U.S. states and their population density. For more information about working with tilesets, see: https://www.mapbox.com/help/studio-manual-tilesets/
NSURL *url = [NSURL URLWithString:@"mapbox://examples.69ytlgls"];
MGLVectorSource *source = [[MGLVectorSource alloc] initWithIdentifier:@"state-source" configurationURL:url];
[style addSource:source];
MGLFillStyleLayer *layer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"state-layer" source:source];
// Access the tileset layer.
layer.sourceLayerIdentifier = @"stateData_2-dx853g";
// Create a stops dictionary. This defines the relationship between population density and a UIColor.
NSDictionary *stops = @{
@0: [MGLStyleValue valueWithRawValue:[UIColor yellowColor]],
@600: [MGLStyleValue valueWithRawValue:[UIColor redColor]],
@1200: [MGLStyleValue valueWithRawValue:[UIColor blueColor]]
};
// Style the fill color using the stops dictionary, exponential interpolation mode, and the feature attribute name.
layer.fillColor = [MGLStyleValue valueWithInterpolationMode:MGLInterpolationModeExponential
sourceStops:stops
attributeName:@"density"
options:@{MGLStyleFunctionOptionDefaultValue: [MGLStyleValue valueWithRawValue:[UIColor whiteColor]]}];
// Insert the new layer below the Mapbox Streets layer that contains state border lines. See the layer reference for more information about layer names: https://www.mapbox.com/vector-tiles/mapbox-streets-v7/
MGLStyleLayer *symbolLayer = [style layerWithIdentifier:@"admin-3-4-boundaries"];
[style insertLayer:layer belowLayer:symbolLayer];
}
- (void)handleTap:(UITapGestureRecognizer *)gesture {
// Get the CGPoint where the user tapped.
CGPoint spot = [gesture locationInView:self.mapView];
// Access the features at that point within the state layer.
NSArray *features = [self.mapView visibleFeaturesAtPoint:spot
inStyleLayersWithIdentifiers:[NSSet setWithObject:@"state-layer"]];
MGLPolygonFeature *feature = features.firstObject;
// Get the name of the selected state.
NSString *state = [feature attributeForKey:@"name"];
[self changeOpacityBasedOn:state];
}
- (void)changeOpacityBasedOn:(NSString*)name {
MGLFillStyleLayer *layer = (MGLFillStyleLayer *)[self.mapView.style layerWithIdentifier:@"state-layer"];
// Check if a state was selected, then change the opacity of the states that were not selected.
if (name.length > 0) {
layer.fillOpacity = [MGLStyleValue valueWithInterpolationMode:MGLInterpolationModeCategorical
sourceStops:@{name: [MGLStyleValue valueWithRawValue:@1]}
attributeName:@"name"
options:@{MGLStyleFunctionOptionDefaultValue: [MGLStyleValue valueWithRawValue:@0]}];
} else {
// Reset the opacity for all states if the user did not tap on a state.
layer.fillOpacity = [MGLStyleValue valueWithRawValue:@1];
}
}
@end
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