ios - 使用 google Direction Api 并请求 json 中的数据时获取 nil 数据

Question

我是 swift 编程和 ios 开发的新手。我正在尝试绘制两个位置之间的路线并遇到此问题。

func getDirections(origin: String!, destination: String!, waypoints: Array<String>!, travelMode: AnyObject!, completionHandler: ((status: String, success: Bool) -> Void)) {
    if let originLocation = origin {
        if let destinationLocation = destination {
            var directionsURLString = baseURLDirections + "origin=" + originLocation + "&destination=" + destinationLocation

            directionsURLString = directionsURLString.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!

            let directionsURL = NSURL(string: directionsURLString)

            dispatch_async(dispatch_get_main_queue(), { () -> Void in
                let directionsData = NSData(contentsOfURL: directionsURL!)

                println(directionsData)

                var error: NSError?
                let dictionary: Dictionary<NSObject, AnyObject> = NSJSONSerialization.JSONObjectWithData(directionsData!, options: NSJSONReadingOptions.MutableContainers, error: &error) as! Dictionary<NSObject, AnyObject>

我收到错误:

fatal error: unexpectedly found nil while unwrapping an Optional value

我尝试打印我收到的数据，结果为零

let baseURLDirections = "https://maps.googleapis.com/maps/api/directios/json?"

Answer 1

您没有在请求网址中包含 API key 。

您可以使用 NSURLSession 执行 Directions API 请求。当您从 API 响应中获取数据时，您可以使用 NSJSONSerialization.JSONObjectWithData() 来解析 JSON 日期。

 func directionAPITest() {

        let directionURL = "https://maps.googleapis.com/maps/api/directions/json?origin=Toronto&destination=Montreal&key=YOUR_API_KEY"
        let request = NSURLRequest(URL: NSURL(string:directionURL)!)
        let session = NSURLSession.sharedSession()
        session.dataTaskWithRequest(request,
            completionHandler: {(data: NSData!, response: NSURLResponse!, error: NSError!) in

                if error == nil {
                    let object = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as! NSDictionary
                    println(object)

                    let routes = object["routes"] as! [NSDictionary]
                    for route in routes {
                        println(route["summary"])
                    }
                    dispatch_async(dispatch_get_main_queue()) {
                      //update your UI here 
                    }
                }
                else {
                    println("Direction API error")
                }

        }).resume()
    }

如果您需要更新 mapView 或 UITableView，您可以在 dispatch_async(dispatch_get_main_queue()) 闭包内执行此操作。