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我正在替换GoogleMaps SDK我Mapbox SDK的 iOS 应用程序。我被困在我的应用程序具有在地图上为折线（已添加）制作动画的功能，例如 Uber 应用程序。

但我似乎无法让它与Mapbox iOS SDK. Mapbox 有一个示例，我可以在地图上添加带有动画的折线坐标，但这不是我想做的。

立即添加折线，但我想为从起点到终点的路线设置动画。

这是我当前来自 Mapbox 示例的代码，用于在带有动画的地图上添加折线坐标。

- (void)addPolylineToStyle:(MGLStyle *)style {
    // Add an empty MGLShapeSource, we’ll keep a reference to this and add points to this later.
    MGLShapeSource *source = [[MGLShapeSource alloc] initWithIdentifier:@"polyline" features:@[] options:nil];
    [style addSource:source];
    self.polylineSource = source;

    // Add a layer to style our polyline.
    MGLLineStyleLayer *layer = [[MGLLineStyleLayer alloc] initWithIdentifier:@"polyline" source:source];
    layer.lineJoin = [NSExpression expressionForConstantValue:@"round"];
    layer.lineCap = layer.lineJoin = [NSExpression expressionForConstantValue:@"round"];
    layer.lineColor = [NSExpression expressionForConstantValue:[UIColor redColor]];

    // The line width should gradually increase based on the zoom level.
    layer.lineWidth = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                       @{@14: @5, @18: @20}];
    [self.mapView.style addLayer:layer];
}

- (void)animatePolyline {
    self.currentIndex = 1;

    // Start a timer that will simulate adding points to our polyline. This could also represent coordinates being added to our polyline from another source, such as a CLLocationManagerDelegate.
    [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(tick:) userInfo:nil repeats:YES];
}

- (void)tick:(NSTimer*)timer {
    if (self.currentIndex > self.locations.count) {
        [timer invalidate];
        return;
    }

    // Create a subarray of locations up to the current index.
    NSArray *currentLocations = [self.locations subarrayWithRange:NSMakeRange(0, _currentIndex)];

    // Update our MGLShapeSource with the current locations.
    [self updatePolylineWithLocations:currentLocations];

    self.currentIndex++;
}

- (void)updatePolylineWithLocations:(NSArray<CLLocation *> *)locations {
    CLLocationCoordinate2D coordinates[locations.count];

    for (NSUInteger i = 0; i < locations.count; i++) {
        coordinates[i] = locations[i].coordinate;
    }

    MGLPolylineFeature *polyline = [MGLPolylineFeature polylineWithCoordinates:coordinates count:locations.count];

    // Updating the MGLShapeSource’s shape will have the map redraw our polyline with the current coordinates.
    self.polylineSource.shape = polyline;
}

更新： 这是我期望做的 gif。

在此处输入图像描述

请帮助我如何为折线的路线设置动画？

谢谢

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1 回答 1

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感谢您使用有用的视觉更新您的问题。您应该能够使用line-gradient在计时器上更新的样式表达式来创建此效果。

虽然没有实现这一点的完美示例，但 Mapbox iOS 团队有一些初始代码显示了此示例 PR 中线渐变表达式的基本语法：https ://github.com/mapbox/ios-sdk-examples/issues /203 . （定义渐变的特定行在这里。）

然后，您可以在计时器上更新MGLLineStyleLayer'.lineColor属性的表达式。

⚠️ 免责声明：我目前在 Mapbox 工作⚠️

于 2019-07-25T14:23:35.360 回答