Time Counter

TimeCounter.swift

struct TimeCounter {
    private var lastTime : Date?
    private(set) var counters : Int = 0
    private(set) var passedTime : TimeInterval = 0.0
    
    mutating func add() {
        guard let previousTime = lastTime else {
            lastTime = Date()
            counters += 1
            return
        }
        
        passedTime += Date().timeIntervalSince(previousTime)
        lastTime = Date()
        counters += 1
    }
    
    var average : TimeInterval {
        guard counters > 1 else { return 0 }
        return passedTime / Double(counters)
    }
}