import Cocoa

/* How many friday the 13th in the year 2023? */
let year = 2023
let calendar = Calendar.current
let dateComponents = DateComponents(year: year, month: 1, day: 1)
let date = calendar.date(from: dateComponents)!
let range = calendar.range(of: .month, in: .year, for: date)!
let months = range.count
var friday13th = 0
for month in 1...months {
    let dateComponents = DateComponents(year: year, month: month, day: 13)
    let date = calendar.date(from: dateComponents)!
    let weekday = calendar.component(.weekday, from: date)
    if weekday == 6 {
        friday13th += 1
    }
}
print(friday13th)

Output

2