Decoding Error when parsing float value from plist when using PropertyListDecoder in Swift

Question

I want have some decimal numbers stored in plist and retrieve them on request.

The plist:





    sessionLength
    1800
    name
    Sleeping
    generators
    
        
            dynamic
            
                amplitude
                40,35,32,30,28,26,22,14,4
                beat
                3.8,3.3,3.0,3.0,2.8,2.6,2.4,2.0,2.0
                carrier
                1:3,1:5,1:6,1:5,1:6,1:5,1:6,1:4,1:3
                type
                0
                isoType
                0
                depth
                40,40,40,40,40,40,40,40,40
            
            static
            
                amplitude
                45
                beat
                2.4
                carrier
                180.6
                depth
                40
                type
                0
                isoType
                0
            
        
        
            dynamic
            
                amplitude
                40,40,40,40,40,40,40,40,40
                beat
                3.8,3.8,3.8,3.8,3.8,3.8,3.8,3.8,3.8
                carrier
                2:3,1:5,1:6,1:5,1:6,1:5,1:6,1:4,1:3
                type
                0
                isoType
                0
                depth
                40,40,40,40,40,40,40,40,40
            
            static
            
                amplitude
                50
                beat
                2
                carrier
                110
                depth
                80
                type
                0
                isoType
                0
            
        
        
            dynamic
            
                amplitude
                40,40,40,40,40,40,40,40,40
                beat
                3.8,3.8,3.8,3.8,3.8,3.8,3.8,3.8,3.8
                carrier
                1:5,1:5,1:6,1:5,1:6,1:5,1:6,1:4,1:3
                type
                1
                isoType
                2
                depth
                70,65,65,50,45,40,40,35,30
            
            static
            
                amplitude
                55
                beat
                4
                carrier
                180
                depth
                90
                type
                0
                isoType
                0

The raw data looks like:

I am using Decodable protocol to retrieve data.

struct PresetData: Decodable {
    private enum CodingKeys: String, CodingKey {
        case name, sessionLength, generators
    }
    
    let name: String
    let sessionLength: Int
    let generators: [PresetStoredData]
}

struct PresetStoredData: Decodable {
    private enum CodingKeys: String, CodingKey {
        case `static`, dynamic
    }
    
    let `static`: PresetStoredItem
    let dynamic: PresetStoredDynamicItem
}

struct PresetStoredItem: Decodable {
    private enum CodingKeys: String, CodingKey {
        case amplitude, beat, carrier, depth, type, isoType
    }
    
    let amplitude: Float
    let beat: Float
    let carrier: Float
    let depth: Float
    
    let type: Int
    let isoType: Int
}

struct PresetStoredDynamicItem: Decodable {
    private enum CodingKeys: String, CodingKey {
        case amplitude, beat, carrier, depth, type, isoType
    }
    
    let amplitude: String
    let beat: String
    let carrier: String
    let depth: String
    
    let type: Int
    let isoType: Int
}

The result is "Parsed property list number <2.4> does not fit in Float."

Edit: the parsing method:

let decoder = PropertyListDecoder()
    return try! decoder.decode(PresetData.self, from: data)

Which kinda does not make sense for me. Any idea what is wrong?

user_1271826 · Answer

Consider





    amplitude
    45.0
    beat
    4.2
    carrier
    180.6

If you decode with:

struct Preset: Decodable {
    let amplitude: Float
    let beat: Float
    let carrier: Float
}

You will receive

dataCorrupted(Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "beat", intValue: nil)], debugDescription: "Parsed property list number <4.2> does not fit in Float.", underlyingError: nil))

But if you change it to Double, it will work:

struct Preset: Decodable {
    let amplitude: Double
    let beat: Double
    let carrier: Double
}

user_5044042 · Answer

Declare the floating point types as Double rather than Float

struct PresetStoredItem: Decodable {
    
    let amplitude: Double
    let beat: Double
    let carrier: Double
    let depth: Double
    
    let type: Int
    let isoType: Int
}

And you can omit the CodingKeys if all keys match the struct names

Decoding Error when parsing float value from plist when using PropertyListDecoder in Swift

2 Answers