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#import "DrawingAGeoJSONLineExample.h"
@import Mapbox;
NSString *const MBXExampleDrawingAGeoJSONLine = @"DrawingAGeoJSONLineExample";
@interface DrawingAGeoJSONLineExample () <MGLMapViewDelegate>
@property (nonatomic) MGLMapView *mapView;
@end
@implementation DrawingAGeoJSONLineExample
- (void)viewDidLoad {
[super viewDidLoad];
self.mapView = [[MGLMapView alloc] initWithFrame:self.view.bounds];
self.mapView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
// Set the map's center coordinate
[self.mapView setCenterCoordinate:CLLocationCoordinate2DMake(45.5076, -122.6736)
zoomLevel:11
animated:NO];
[self.view addSubview:self.mapView];
// Set the delegate property of our map view to self after instantiating it.
self.mapView.delegate = self;
[self drawPolyline];
}
- (void)drawPolyline {
// Perform GeoJSON parsing on a background thread
dispatch_queue_t backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(backgroundQueue, ^(void) {
// Get the path for example.geojson in the app's bundle
NSString *jsonPath = [[NSBundle mainBundle] pathForResource:@"example" ofType:@"geojson"];
// Convert the file contents to a shape collection feature object
NSData *data = [[NSData alloc] initWithContentsOfFile:jsonPath];
MGLShapeCollectionFeature *shapeCollectionFeature = (MGLShapeCollectionFeature *)[MGLShape shapeWithData:data encoding:NSUTF8StringEncoding error:NULL];
MGLPolylineFeature *polyline = (MGLPolylineFeature *)shapeCollectionFeature.shapes.firstObject;
// Optionally set the title of the polyline, which can be used for:
// - Callout view
// - Object identification
// In this case, set it to the name included in the GeoJSON
polyline.title = polyline.attributes[@"name"]; // "Crema to Council Crest"
// Add the polyline to the map, back on the main thread
// Use weak reference to self to prevent retain cycle
__weak typeof(self) weakSelf = self;
dispatch_async(dispatch_get_main_queue(), ^(void) {
[weakSelf.mapView addAnnotation:polyline];
});
});
}
- (CGFloat)mapView:(MGLMapView *)mapView alphaForShapeAnnotation:(MGLShape *)annotation {
// Set the alpha for all shape annotations to 1 (full opacity)
return 1.0f;
}
- (CGFloat)mapView:(MGLMapView *)mapView lineWidthForPolylineAnnotation:(MGLPolyline *)annotation {
// Set the line width for polyline annotations
return 2.0f;
}
- (UIColor *)mapView:(MGLMapView *)mapView strokeColorForShapeAnnotation:(MGLShape *)annotation {
// Set the stroke color for shape annotations
// ... but give our polyline a unique color by checking for its `title` property
if ([annotation.title isEqualToString:@"Crema to Council Crest"]) {
// Mapbox cyan
return [UIColor colorWithRed:59.0f/255.0f green:178.0f/255.0f blue:208.0f/255.0f alpha:1.0f];
} else {
return [UIColor redColor];
}
}
@end
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