Appointments.swift

// Put this in a Swift playground

import Foundation

class Appointment {
    var start: Date
    var end: Date
    
    init(start: Date, end: Date) {
        // Ensure that start is always before end
        if start <= end {
            self.start = start
            self.end = end
        } else {
            self.end = start
            self.start = end
        }
    }
    
    func conflicts(with other: Appointment) -> Bool {
        var appt1: Appointment
        var appt2: Appointment
        
        // Ensure that appt1 starts before or at the same time as appt2
        if self.start <= other.start {
            appt1 = self
            appt2 = other
        } else {
            appt1 = other
            appt2 = self
        }
        
        if appt1.end > appt2.start {
            return true
        }
        
        return false
    }
    
    var description: String {
        return "\(self.start, self.end)"
    }
}

let appt1 = Appointment(start: 2, end: 2);
appt1.description
let appt2 = Appointment(start: 2, end: 4);
appt2.description

print(appt1.conflicts(with: appt2))