ios - Swift MKAnnotationView maskToBounds 抛出错误

Question

问题
目前我正在尝试将自定义图像添加到 AnnotationPoint。我目前正在使用它，但我想为其添加圆边。当我尝试设置代码 maskToBounds = true 时，我抛出了一个错误(我相信是因为它在主线程中被调用)。当我尝试制作一个临时的 AnnotationView 时，在 viewDidLoad 中我将它的 masksToBounds 属性设置为 true，并且它有效，但仅适用于 1 人图像，当我放大 map 时它会消失。我需要帮助的是弄清楚如何修复错误

我尝试过的

    //sets the pictures on the map from a url
    func mapView(mapView: MKMapView!, viewForAnnotation annotation: MKAnnotation!) -> MKAnnotationView! {
        if !(annotation is CustomPointAnnotation) {
            return nil
        }

        let reuseId = "Profile Picture"

        var anView = mapView.dequeueReusableAnnotationViewWithIdentifier(reuseId)
        if anView == nil {
            anView = MKAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
            anView.canShowCallout = true
        }
        else {
            anView.annotation = annotation
        }

        //Set annotation-specific properties **AFTER**
        //the view is dequeued or created...
        let cpa = annotation as! CustomPointAnnotation
        if let url = NSURL(string: cpa.urlName) {
            if let data = NSData(contentsOfURL: url){
                anView.image =  UIImage(data: data)
            }

    }

        //resize the users friends profile pictures
        var cropSquare = CGRectMake(0, 0, anView.image.size.width / 3, anView.image.size.height / 3)
        UIGraphicsBeginImageContextWithOptions(cropSquare.size, false, 1.0)
        anView.image.drawInRect(cropSquare)
        anView.image = UIGraphicsGetImageFromCurrentImageContext()
        anView.layer.masksToBounds = true
        anView.layer.cornerRadius = 10

        return anView
}

错误
线程1:信号SIGABRT

Answer 1

    //make the images circles
    var imageView: UIImageView = UIImageView(image: anView.image)
    var layer: CALayer = CALayer()
    layer = imageView.layer
    layer.masksToBounds = true
    layer.cornerRadius = CGFloat(anView.image.size.width / 2)
    UIGraphicsBeginImageContext(imageView.bounds.size)
    layer.renderInContext(UIGraphicsGetCurrentContext())
    var roundedImage = UIGraphicsGetImageFromCurrentImageContext()
    anView.image = roundedImage
    UIGraphicsEndImageContext()