迭代从S3

Question

我正在尝试使用从S3下载的JSON文件的内容填充表（使用AWS SDK）。我在循环notifications数组时遇到了困难，因为它似乎不是一个可迭代的对象。将整个对象强制转换为字典时返回Nil。我收到一条错误，指出我不能将notifications字符串作为数组进行类型转换。我怎样才能将notifications对象转换成我可以迭代的东西？

//JSON file
{
   "notifications": [
       {
          "startDate": "2016-10-01 00:00:00",
          "endDate": "2016-10-31 23:59:59",
          "message": "October"
       },
       {
          "startDate": "2016-11-01 00:00:00",
          "endDate": "2016-11-31 23:59:59",
          "message": "November"
       }
   ]
}

//I omitted extraneous code
let task = s3.getObject(getObjectRequest)

if let output = task.result as? AWSS3GetObjectOutput{
    do{
        let json = try NSJSONSerialization.JSONObjectWithData((output.body! as? NSData)!, options: .AllowFragments)

        //Debug code that works
        print(json["notifications"]![0]) //Prints the first notification
        print(json["notifications"]![0]["startDate"])

        //Debug code that does not work
        let opt = json["notifications"] as! NSArray  //Can't typecast String as Array

        //A 'for' loop does not work as well.
    }catch{
        print("Error serializing JSON [\(error)]")
    }
}

Answer 1

让opt = json [＆＃34;通知＆＃34;]为？数组//不能将字符串转换为数组

请试试这个

Answer 2

json["notifications"] as! NSArray工作但是你必须首先将NSJSONSerialization的结果转换为正确的类型，在你的情况下是字典：

do {
    if let json = try JSONSerialization.jsonObject(with: data, options: []) as? [String:AnyObject] {
        print(json["notifications"] as! NSArray)
    }
} catch let error as NSError {
    print(error.debugDescription)
}

或者，如果您愿意：

do {
    if let json = try JSONSerialization.jsonObject(with: data, options: []) as? NSDictionary {
        print(json["notifications"] as! NSArray)
    }
} catch let error as NSError {
    print(error.debugDescription)
}