在Swift中从数组中获取项目

Question

我对Swift很新，并且花了几个小时试图从JSON响应中提取photo_url密钥。

我正在使用它来阅读JSON：

let jsonDictionary = try JSONSerialization.jsonObject(with: data, options: .mutableContainers)

然后：

                if let eventsDictionary = jsonDictionary {
                    let upcomingEvents = UpcomingEvents(eventsDictionary: eventsDictionary)
                    completion(upcomingEvents)
                } else {
                    completion(nil)
                }

这是我（失败）尝试拔出钥匙：

init(eventsDictionary: [String : Any]) {
    //photoUrl = eventsDictionary[EventKeys.photoUrl] as? String
    let groups: NSArray = eventsDictionary["groups"] as! NSArray
    let url: String = groups[0]
   print("THIS IS YOUR RETURNED PHOTO URL--\(url)--END OF RETURNED PHOTO URL")
}

我将“[String：Any]”更改为[String：AnyObject]，现在我得到了这个......

Answer 1

向NSArray投射Any会有问题。只需使用[String：AnyObject]使您的Init方法。但是，最好在这里使用Array而不是NSArray

Answer 2

尝试使用以下代码获取网址。

let firstObj  = groups[0] as! [String: String] // use if let to unwrap is better
let url = firstObj["photo_url"]

Answer 3

要从照片中的json文件中获取“photo_url”，

它看起来像这样：

init(eventsDictionary: [String : Any]) {
   if let groups = eventsDictionary["groups"] as? [NSDictionary]{
        /*
        // Get All URL
        var urls : [String] = []
        for group in groups{
            if let url = group.value(forKey: "photo_url"){
                urls.append(url)
            }
        }
        */

        // Groups[0] url
        let url: String = groups[0].value(forKey: "photo_url") as! String
        print("THIS IS YOUR RETURNED PHOTO URL--\(url)--END OF RETURNED PHOTO URL")
    }
}

Answer 4

你需要把json读作`[String：Any]。

 if let eventsDictionary = json as? [String: Any] {
     let upcomingEvents = UpcomingEvents(eventsDictionary: eventsDictionary)
     completion(upcomingEvents)               
 }

然后，像这样初始化您的UpcomingEvents模型

init(eventsDictionary: [String : Any]) {
    let groups: NSArray = eventsDictionary["groups"] as! NSArray
    let group1 = groups[0] as! NSDictionary
    let photoURL = group1["photo_url"] as! String
    print(photoURL)
}