PerceptronTrainer.swift

struct PerceptronTrainer {
    let data: [PerceptronDataPair]
    
    func train(inout p: Perceptron) -> Int {
        var error: Int = 0
        for d in data {
            error = p.backProp(d.input, output: d.output)
        }
        return error
    }
}

PerceptronTrainingData.swift

struct PerceptronDataPair {
    let input: [Double]
    let output: Int
}