如何将SMCalloutView的宽度调整为字幕的长度？

Question

我正在使用google maps SDK＆amp ;;快速实现iOS应用程序SMCalloutView。 当显示字幕SMCalloutView的长文本时，我想知道如何通过折叠文本来显示它。

我的代码摘录如下。

@IBOutlet weak var mapView: GMSMapView!
var calloutView = SMCalloutView()
var emptyCalloutView: UIView!

override func viewWillAppear(animated: Bool) {
    var marker = GMSMarker()
    marker.title = "Tokyo Tower"
    marker.snippet = "subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle subtitle "
    marker.position = CLLocationCoordinate2DMake(35.658582, 139.745433)
    marker.map = self.mapView
    self.mapView.selectedMarker = marker

    let camera = GMSCameraPosition.cameraWithLatitude(marker.position.latitude, longitude: marker.position.longitude, zoom: kZoomLevel)
    self.mapView.camera = camera
}

func mapView(mapView: GMSMapView, markerInfoWindow marker: GMSMarker) -> UIView {
    let anchor:CLLocationCoordinate2D = marker.position
    let point:CGPoint = mapView.projection.pointForCoordinate(anchor)

    self.calloutView.title = marker.title
    self.calloutView.subtitle = marker.snippet
    self.calloutView.calloutOffset = CGPointMake(0, -kCalloutYOffset)
    self.calloutView.hidden = false

    var calloutRect: CGRect = CGRectZero
    calloutRect.origin = point
    calloutRect.size = CGSizeZero
    self.calloutView.presentCalloutFromRect(calloutRect, inView: mapView, constrainedToView: mapView, animated: true)

    return self.emptyCalloutView
}

任何建议都是相关的。提前谢谢。