How to convert Firebase Array to Swift Array?

Question

I am reading data from Firebase Data Snapshot which contains an array. I was downcasting this snapshot as [String: AnyObject] into a variable say fetchedDict. Now I want to convert the sensorValues to an swift readable array. I checked dynamicType of sensorValues

print(fetchedDict!["sensorValues"].dynamicType)

It is Optional
I have tried two approaches to convert it in array:

Downcasting it to NSArray, [Int] but it didnt work.
Wrote a mirror function(see at the end) which worked on playground but sadly not in iOS App. It gave me Could not cast value of type 'Swift.Array' (0x117a24028) to 'Swift.Int'.

Can someone please guide me to solve this? Thanks!

rootRef!.observeEventType(.Value, withBlock: { (snapshot) in

        for child in snapshot.children.allObjects {
            let snap = child as! FIRDataSnapshot
            let fetchedDict = snap.value as? [String: AnyObject]
})

This is the fetchedDict:

[
    "activityDuration": 15;
    "sensorValues":   (
        5,
        24,
        24,
        13,
        22,
        4,
        42,
        13,
        3,
        4
    );
    "timestamp": 20160713184023;
]

Mirror Function which didnt work in the iOS app. Tried Any as well as AnyObject as argument type. This code works in playground though.

func tupleToArray(sensorValues: Any) -> [Int] {
    let mirror = Mirror(reflecting: sensorValues)
    var arr = [Int]()
    for child in mirror.children{
        let stringedValue = (child.value) as! Int
        arr.append(stringedValue)
    }
    return arr
 }

does looping through like this work? for i in fetchedDict!["sensorValues"] as! Int — jacob bullock
– jacob bullock, Commented Jul 14, 2016 at 11:20
@ÖzgürErsil Tried it too...it gives warning Cast from child to unrelated type 'int' always fails. And when i call the function - Execution was interrupted. — Ryan Cyrus
– Ryan Cyrus, Commented Jul 14, 2016 at 11:30
@jacobbullock no, it doesn't work because it does not conform to protocol seuqenceType. — Ryan Cyrus
– Ryan Cyrus, Commented Jul 14, 2016 at 11:33
@RyanCyrus how are you fetching that dict? Is that json converting to a dictionary? — jacob bullock
– jacob bullock, Commented Jul 14, 2016 at 11:37

Jay · Accepted Answer · 2016-07-14 19:13:30Z

4

Can you just read in as NSArray and then make a Swift array out of it?

Given

array_node
  0: "index 0"
  1: "index 1"
  2: "index 2"

and to read it

    let myRef = self.myRootRef.childByAppendingPath("array_node")
    myRef.observeSingleEventOfType(.Value, withBlock: { snapshot in

        let a = snapshot.value as! NSArray
        print(a)

        let b = (a as Array).filter {$0 is String}

        print(b)
    })

the output is

(
    "index 0",
    "index 1",
    "index 2"
)
[index 0, index 1, index 2]

edited Jul 14, 2016 at 19:13

answered Jul 14, 2016 at 18:12

Jay

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1 Comment

Ryan Cyrus Over a year ago

Yes, I could have.. but i am iterating through all children. But now i realize i can use conditional checking with what you suggested. Thanks! :)

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