Comparing Swift Dates by Year

Try using DateComponents:

let components = Calendar.current.dateComponents([.year], from: Date(), to: secondDate)
print(components.year)

This should do what you're asking:

func dateIsNYearsBeforeDate(date1: Date, date2: Date, nYears: Int) -> Bool {
    let calendar = Calendar.current

    // Extract the components of the dates
    let date1Components = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date1)
    let date2Components = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date2)

    // Check if the dates are in the same month and day
    let isSameMonth = date1Components.month == date2Components.month
    let isSameDay = date1Components.day == date2Components.day

    // Skip this if you want to check only the date and not the time
    let isSameHour = date1Components.hour == date2Components.hour
    let isSameMinute = date1Components.minute == date2Components.minute
    let isSameSecond = date1Components.second == date2Components.second

    let yearsDifference = date2Components.year! - date1Components.year!

    return isSameMonth && isSameDay && isSameHour && isSameMinute && isSameSecond && yearsDifference == nYears
}

Here's the code to check if 2 dates is greater than X years. Hopefully the comments will help you understand the process. Understand the logic and modify it to suit your needs.

func isPastXYears(_ numberOfYears : Int) -> Bool{

    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy/MM/dd"

    //Determine PastDate and NowDate
    guard let pastDate = formatter.date(from: "2015/06/28") else { return false}
    let nowDate = Date()

    //Convert the dates to TimeInterval for comparing
    let pastDateTimeInterval = pastDate.timeIntervalSinceNow
    let nowDateTimeInterval = nowDate.timeIntervalSinceNow

    //Get the TimeInterval of X years
    let xYearsTimeInterval : TimeInterval = 60 * 60 * 24 * 365 * Double(numberOfYears) // seconds * minutes * hoursInADay * numberOfDaysInAYear * numberOfYears

    //Get the difference of the dates' timeinterval
    let timeIntervalDifference = nowDateTimeInterval - pastDateTimeInterval

    //Check if difference is > xYearsInterval
    return (timeIntervalDifference >= xYearsTimeInterval)
}

isPastXYears(3) //true
isPastXYears(4) //false

In Swift 5.0, you can compare Date structs as it conforms to Equatable and Comparable. This means you can do something like:

let now = Date()
let theFuture = Date().addingTimeInterval(100)

and check it like so:

now == theFuture
now != theFuture
now < theFuture
now > theFuture

Reference

Use DateComponents, like in the snippet below:

let monthsToAdd = 2
let daysToAdd = 1
let yearsToAdd = 1
let currentDate = Date()

var dateComponent = DateComponents()

dateComponent.month = monthsToAdd
dateComponent.day = daysToAdd
dateComponent.year = yearsToAdd

let futureDate = Calendar.current.date(byAdding: dateComponent, to: currentDate)

print(currentDate)
print(futureDate!)

I would probably do something like this:

let date1 = Date()
let date2 = Date()

let dateMinus3Years = Calendar.current.date(byAdding: .year, value: -3, to: date1)!
let datePlus3Years = Calendar.current.date(byAdding: .year, value: 3, to: date1)!
let condition = Calendar.current.isDate(date2, inSameDayAs: dateMinus3Years)
   || Calendar.current.isDate(date2, inSameDayAs: datePlus3Years)

or

let date1 = Date()
let date2 = Date()

let date1Components = Calendar.current.dateComponents([.year, .month, .day], from: date1)
let date2Components = Calendar.current.dateComponents([.year, .month, .day], from: date2)

let condition = abs(date1Components.year! - date2Components.year!) == 3
    && date1Components.month == date2Components.month
    && date1Components.day == date2Components.day

This will be safer than using time differences.