Looping through Arrays in Dictionaries

July 22, 2023

Typical noob disclaimer goes here 😉 I am trying to nest an array in a Swift dictionary similar to how you would with JSON. My nested array ("blocks" in the code below) has mixed datatypes in it. When I run my For-in loop on it, I get the error For-in loop requires ‘Any’ to conform to ‘Sequence’ which sounds like it’s helpful – but I’m not sure what to do here. Would love some advice.

My dict:

let levelOneData = [
    "goal": 180,
    "gravity": CGVector(dx: 0.0, dy: -4.0),
    "bombs": 12,
    "blocks": [
        0: [
            "blockSize": "Small",
            "blockPosition": [0, 80],
            "blockIsLocked": false
        ] as [String : Any],
        1: [
            "blockSize": "Medium",
            "blockPosition": [0, 0],
            "blockIsLocked": false
        ] as [String : Any],
    ]
] as [String : Any]

My For loop:

for (index, block) in levelOneData["blocks"]! { <<<< error here
    print(block) 
}

>Solution :

Because the semicyclic form of levelOneData["blocks"]! is Any type, you must explicitly declare the type for use in a repeating statement such as for-in.

Referring to the content of levelOneData at the top, it seems appropriate to use [Int: [String: Any]] as the type casting.
Please refer to the example code below.

    func printData() {
        if let data = levelOneData["blocks"] as? [Int: [String: Any]] {
            for (index, block) in data {
                print(block)
            }
        }
    }

    func printData() {
        guard let data = levelOneData["blocks"] as? [Int: [String: Any]] else {
            return
        }
        
        for (index, block) in data {
            print(block)
        }
    }