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我对swift很陌生,试图在地图上显示折线。Swift MKDirections calculateDirectionsWithCompletionHandler崩溃
环顾四周后,发现这个代码:
let directions = MKDirections(request: request)
directions.calculateDirectionsWithCompletionHandler { [unowned self] response, error in
guard let unwrappedResponse = response else { return }
for route in unwrappedResponse.routes {
self.mapView.addOverlay(route.polyline)
}
它可以作为预期,但应用程序崩溃(EXC_BAD_ACCESS)如果绘制前行用户返回。