Vfrdtyky

I have following format data (atleast 100,000 of these data blocks) in my database :

{

  "ax" : 1.232,

  "ay" : 1.897,

  "az" : -0.232

  "timestamp" : 151232326789

 }

which i am retrieving in my iOS Application in the format of a dictionary and parsing to a class model.
The above data is from sensor MPU6050, communicating to firebase usgin NodeMCU. Since NodeMCU doesnt have its own clock, to give the timestamp to data using ServerValue.Timestamp was the only option. Thus i couldn't properly structure my JSON Data that i now need to format on my iOS Application.

I am extracting the time and date from the timestamp in my database

This is the format i need in my frontend :

{

  Date1 : {

          Time1 :{ 

                "ax" : 1.232,

                "ay" : 1.897,

                "az" : -0.232

                  },

          Time2 :{ 

                "ax" : 1.232,

                "ay" : 1.897,

                "az" : -0.232

                  },

          Time3 :{ 

                "ax" : 1.232,

                "ay" : 1.897,

                "az" : -0.232

                  },

          Time4 :{ 

                "ax" : 1.232,

                "ay" : 1.897,

                "az" : -0.232

                  }

            }

  Date2 : {...similar as above.}

   }

I have tried using NSMutableDictionary, but data is getting messed up. Any Solution?

I would structure this as one entity holding the sensor data for one date in an an array and storing instances of that entity in an array since dictionaries are unsorted.

var allData: [OneDayData]



struct OneDayData {

    var date: Date

    var sensorData: [SensorData]

}



struct SensorData {

    var time: String

    var ax: Double

    var ay: Double

    var az: Double

}

Note, I don't know how you convert the timestamp so I simply assumed it got converted into a Date and a String

import Foundation



// define date - time interval for testing

let start = Calendar.current.date(from: DateComponents(year: 2018, month: 1, day: 1))

let end = Calendar.current.date(from: DateComponents(year: 2018, month: 1, day: 3))

let s = start!.timeIntervalSinceReferenceDate

let e = end!.timeIntervalSinceReferenceDate



// generate array of random data with timestamp from defined date - time interval

var data: [[String: Double]] = 

(0..<10).forEach { _ in

    let ax = Double.random(in: -1.0...1.0)

    let ay = Double.random(in: -1.0...1.0)

    let az = Double.random(in: -1.0...1.0)

    // stamp between start and end date, with one second resolution

    let timestamp = TimeInterval.random(in: s...e).rounded()

    let record = ["ax": ax, "ay": ay, "az": az, "timestamp": timestamp]

    data.append(record)

}

What I got with print(data as NSArray)?

(

        {

        ax = "-0.9915295335923959";

        ay = "0.04220588780831558";

        az = "0.04947324263041164";

        timestamp = 536480749;

    },

        {

        ax = "0.8339518841345668";

        ay = "-0.8796254984325194";

        az = "0.9274526027609205";

        timestamp = 536596358;

    },

        {

        ax = "0.1892933660394962";

        ay = "0.2786212981444189";

        az = "-0.7010853895168836";

        timestamp = 536453459;

    },

        {

        ax = "-0.3879536539762585";

        ay = "-0.9881198368284949";

        az = "-0.8103733151058379";

        timestamp = 536574669;

    },

        {

        ax = "0.4386373099712233";

        ay = "-0.1082200532953461";

        az = "-0.5452489312143274";

        timestamp = 536515655;

    },

        {

        ax = "0.1021774847462089";

        ay = "-0.6414676993950421";

        az = "0.8826716373674426";

        timestamp = 536455164;

    },

        {

        ax = "0.1877861732407253";

        ay = "-0.6069605631703257";

        az = "-0.3766270018644693";

        timestamp = 536569833;

    },

        {

        ax = "0.3011539934614316";

        ay = "-0.8534914632655413";

        az = "0.652288374381045";

        timestamp = 536477646;

    },

        {

        ax = "-0.3087207248856481";

        ay = "0.566261641115348";

        az = "-0.6320769324182691";

        timestamp = 536563296;

    },

        {

        ax = "-0.5450288945879682";

        ay = "0.6143645223909975";

        az = "-0.8973854689667276";

        timestamp = 536609836;

    }

)

Now I have the data in the "same format" as you received (not JSON, but a Swift's Array of Dictionaries) and with a little help of next simple function

// extract date and time from timestamp value

func stamp(timestamp: TimeInterval)->(date: String, time: String) {

    let date = Date(timeIntervalSinceReferenceDate: timestamp)

    return (DateFormatter.localizedString(from: date, dateStyle: .short, timeStyle: .none),

    DateFormatter.localizedString(from: date, dateStyle: .none, timeStyle: .medium))

}

we are ready to group your data values by date and time, as required

// group data by date and time, if duplicated timestamp, use last value only

let result = data.reduce(into: [String:[String:[String: Double]]]()) { (result, record) in

    guard let ts = record["timestamp"] else { return }

    var record = record

    record["timestamp"] = nil

    let (date, time) = stamp(timestamp: ts)

    if result[date] == nil {

        result[date] = [time : record]

    } else {

        result[date]?[time] = record

    }

}

See how the result [String:[String:[String: Double]]] looks printed as NSDictionary

{

    "01/01/2018" =     {

        "00:50:59" =         {

            ax = "0.1892933660394962";

            ay = "0.2786212981444189";

            az = "-0.7010853895168836";

        };

        "01:19:24" =         {

            ax = "0.1021774847462089";

            ay = "-0.6414676993950421";

            az = "0.8826716373674426";

        };

        "07:34:06" =         {

            ax = "0.3011539934614316";

            ay = "-0.8534914632655413";

            az = "0.652288374381045";

        };

        "08:25:49" =         {

            ax = "-0.9915295335923959";

            ay = "0.04220588780831558";

            az = "0.04947324263041164";

        };

        "18:07:35" =         {

            ax = "0.4386373099712233";

            ay = "-0.1082200532953461";

            az = "-0.5452489312143274";

        };

    };

    "02/01/2018" =     {

        "07:21:36" =         {

            ax = "-0.3087207248856481";

            ay = "0.566261641115348";

            az = "-0.6320769324182691";

        };

        "09:10:33" =         {

            ax = "0.1877861732407253";

            ay = "-0.6069605631703257";

            az = "-0.3766270018644693";

        };

        "10:31:09" =         {

            ax = "-0.3879536539762585";

            ay = "-0.9881198368284949";

            az = "-0.8103733151058379";

        };

        "16:32:38" =         {

            ax = "0.8339518841345668";

            ay = "-0.8796254984325194";

            az = "0.9274526027609205";

        };

        "20:17:16" =         {

            ax = "-0.5450288945879682";

            ay = "0.6143645223909975";

            az = "-0.8973854689667276";

        };

    };

}

JSON part is up to you.

Dictionary won't solve your problem. What you need here is array of custom models.

For example,

struct Time {

    var ax: Float

    var ay: Float

    var az: Float

}



struct Date {

    var times: [Time]

}



let array: [Date] = ... // parse your json into this

You need to write parsing logics of your json into this structure which can be done in various ways and, I believe, is out of the scope of initial question

• 
  

  jsonResponse is your array

  
  
  

          if let dictionary = jsonResponse as? [String : Any]
  
          {
  
  
  
                      let all=dictionary["Date1"] as? [[String : Any]]
  
                       if let all = all
  
                       {
  
  
  
                          let user:[String:Any]=all[0]["Time1"]! as! [String : Any]
  
                          let user2:[String:Any]=all[0]["Time2"]! as! [String : Any]
  
  
  
                          print(user["ax"] as? String)!,user["ay"] as? String)!,user["az"] as? String)!)                          
  
                          print(user2["ax"] as? String)!,user2["ay"] as? String)!,user2["az"] as? String)!)                            
  
  
  
                       }
  
  
  
          }