Understanding Google Maps SDK and Showing Arrows on MapView

Google Maps SDK provides an extensive set of APIs for developers to integrate maps into their applications. In this article, we’ll delve into the specifics of using GMSMapView and explore how to display arrows on the map to indicate driving directions.

Setting Up the Google Maps SDK

Before diving into the nitty-gritty details, it’s essential to understand how to set up the Google Maps SDK in your project. Here’s a step-by-step guide:

1. Create a Google Cloud Console Project: Head over to the Google Cloud Console and create a new project. Follow the prompts to set up your project, including enabling the Google Maps JavaScript API.

2. Get Your API Key: Navigate to the “Navigation menu” (three horizontal lines in the top left corner) and click on “APIs & Services” > “Dashboard”. Click on the “Enable APIs and Services” button and search for “Google Maps JavaScript API”. Select it, then click on the “Enable” button.

3. Get Your API Key: Under the “APIs & Services” section, click on “Credentials” and then click on “Create Credentials” > “OAuth client ID”. Choose “Web application” as the application type, enter a authorized JavaScript origins, and click on “Create”.

4. Get Your Client ID: After creating your OAuth client ID, you’ll see a prompt to create a new Android key for Google Maps. This is necessary because GMSMapView relies on this key to function correctly.

5. Add the SDK to Your Project: Add the following line of code to your project’s build.gradle file:

dependencies { implementation ‘com.google.android.gms:maps:20.0.0’ }

## Understanding GMSMapView and Driving Directions

GMSMapView is a powerful tool for displaying maps in Android applications. When it comes to driving directions, you'll want to use the `animateToBearing` method to change the bearing of the map.

Here's an example of how to use `animateToBearing`:

```markdown
- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading{
    if(newHeading.headingAccuracy>0)
    {
        float heading = newHeading.magneticHeading; //in degrees
        [mapView animateToBearing:heading];
    }
}

In the above code snippet, we’re updating the map’s bearing to match our current location. The animateToBearing method takes a single parameter, which is the new bearing of the map.

Converting Magnetic Heading to Degrees

One common misconception when working with magnetic headings is that you need to convert it from degrees to radians using the formula radians = degrees * M_PI / 180. However, this isn’t necessary in most cases.

The newHeading object returned by your delegate method already contains a value of type CLLocationDirection, which can be used directly with the animateToBearing method. Here’s why:

• The animateToBearing method requires a CLLocationDirection as its parameter.
• The newHeading object provides access to a magneticHeading or trueHeading property, both of which are objects of type CLLocationDirection.
• These two properties can be used directly with the animateToBearing method without needing any conversion.

Understanding CLLocationDirection

Let’s take a closer look at the CLLocationDirection class and its usage in the context of animateToBearing.

@interface CLDirection : NSObject {
    double _degrees;
}
@property (nonatomic, assign) double degrees; //the direction of the current location (in degrees)
- (instancetype)initWithDegrees:(double)degrees; //init a new instance
@end

In this code snippet, we can see that CLLocationDirection is an object with a single property called degrees, which represents the direction of the current location in degrees.

When you use animateToBearing:, the method takes a value of type CLLocationDirection as its parameter. This value is then used to update the map’s bearing.

Best Practices for Using animateToBearing

Here are some best practices to keep in mind when using animateToBearing:

• Use newHeading.magneticHeading or newHeading.trueHeading: These properties provide access to a value of type CLLocationDirection, which can be used directly with the animateToBearing method.
• Don’t convert magnetic heading to degrees: As mentioned earlier, this isn’t necessary in most cases. Instead, use the animateToBearing:, method to update the map’s bearing based on the provided value of type CLLocationDirection.
• Set a suitable heading filter: If you’re using the headingFilter property to limit the frequency of updates to the map’s bearing, make sure it’s set to a suitable value. This will help prevent excessive battery drain and improve performance.

Conclusion

In this article, we explored how to display arrows on GMSMapView to indicate driving directions. We covered the basics of using animateToBearing and explained why you don’t need to convert magnetic headings from degrees. By following these best practices and understanding the intricacies of the Google Maps SDK, you’ll be able to create engaging and interactive maps that provide an excellent user experience.

Table of Contents

1. Setting Up the Google Maps SDK
2. Understanding GMSMapView and Driving Directions
3. Converting Magnetic Heading to Degrees
4. Understanding CLLocationDirection
5. [Best Practices for Using animateToBearing](#best-practices-for-using-animate Tobearing)

Last modified on 2023-07-04