Swift 3 向 MKMapSnapShotter 快照添加自定义注释引脚 [英] Swift 3 Add custom annotation pin to MKMapSnapShotter snapshot

问题描述

我正在自己学习 Swift 3，我当前的学习项目涉及允许用户拍摄照片并获取固定当前位置的地图快照.

我依赖于

I'm learning Swift 3 on my own, and my current learning project involves allowing the user to snap a photo and get a map snapshot with the current location pinned.

I've relied on this answer from Aug 2015 and this answer from Jun 2016 for guidance, but I still can't find the right path.

Right now, I can...

1. Get the photo from the buffer
2. Get a map snapshot

But I just can't place the pin. I know that my code is incomplete and ineffective -- so this is more than just a debugging question. Here is what I've been working with (as well as many variations based on the links above):

let snapShotter = MKMapSnapshotter(options: mapSnapshotOptions)

snapShotter.start() {

    snapshot, error in

        guard let snapshot = snapshot else {
            return
        }

        let image = snapshot.image
        let annotation = MKPointAnnotation()
        annotation.coordinate = needleLocation  // is a CLLocationCoordinate2D
        annotation.title = "My Title"

        let annotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: "annotation")

        // I want to push the final image to a global variable
        // can't figure out how to define finalImage as the pinned map
        self.myMap = finalImage


        } // close snapShotter.start

I've been stuck for days now, so I certainly would appreciate any insights. Thanks!

解决方案

To render a MKMapSnapshot with annotation views, you have to manually draw the snapshot's image and the annotation view's image on a new graphic context, and get a new image from that context. In Swift 3:

let rect = imageView.bounds

let snapshot = MKMapSnapshotter(options: options)
snapshot.start { snapshot, error in
    guard let snapshot = snapshot, error == nil else {
        print(error ?? "Unknown error")
        return
    }

    let image = UIGraphicsImageRenderer(size: options.size).image { _ in
        snapshot.image.draw(at: .zero)

        let pinView = MKPinAnnotationView(annotation: nil, reuseIdentifier: nil)
        let pinImage = pinView.image

        var point = snapshot.point(for: location.coordinate)

        if rect.contains(point) {
            point.x -= pinView.bounds.width / 2
            point.y -= pinView.bounds.height / 2
            point.x += pinView.centerOffset.x
            point.y += pinView.centerOffset.y
            pinImage?.draw(at: point)
        }
    }

    // do whatever you want with this image, e.g.

    DispatchQueue.main.async {
        imageView.image = image
    }
}

This was adapted from https://stackoverflow.com/a/18776723/1271826, which itself was adapted from WWDC 2013 video Putting MapKit in Perspective.

Here is an example of a snapshot with a .satelliteFlyover:

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