How to get 1 hour ago from a date in iOS swift?

Question

I have been researching, but I couldnt find exact solution for my problem. I have been trying to get 1 hour ago from a date. How can I achieve this in swift?

Answer 1

Details

• Xcode 11.4 (11E146), Swift 5.2

Solution

import Foundation

extension Date {

    typealias Component = (value: Int, type: Calendar.Component)

    init?(bySubtracting components: Component..., calendar: Calendar = Calendar.current, from date: Date) {
        guard let date = date.subtract(components, calendar: calendar) else { return nil }
        self = date
    }

    func subtract(_ components: Component..., calendar: Calendar = Calendar.current) -> Date? {
        subtract(components, calendar: calendar)
    }

    func subtract(_ components: [Component], calendar: Calendar = Calendar.current) -> Date? {
        components.reduce(self) { (result, component) -> Date? in
            guard let date = result else { return nil }
            return calendar.date(byAdding: component.type, value: (-1)*component.value, to: date)
        }
    }

    static func beforeNow(difference component: Component..., calendar: Calendar = Calendar.current) -> Date? {
        Date().subtract(component, calendar: calendar)
    }

    static func beforeNow(difference component: [Component], calendar: Calendar = Calendar.current) -> Date? {
        Date().subtract(component, calendar: calendar)
    }
}

extension Date {
    static func - (date: Date, component: Date.Component) -> Date? { date.subtract(component, calendar: Calendar.current) }
    static func -= (date: inout Date, component: Date.Component) {
        guard let newDate = date.subtract(component, calendar: Calendar.current) else { return }
        date = newDate
    }
}

Usage

var currentDate = Date()
let date1 = Date(bySubtracting: (30, .day), from: currentDate)

let date2 = Date().subtract((30, .day))

let date3 = Date().subtract([(1, .minute), (2, .hour), (3, .day), (4, .month)])

let component = Date.Component(value: 1, type: .day)
let date4 = Date.beforeNow(difference: component)

let date5 = Date.beforeNow(difference: (1, .minute), (2, .hour), (3, .day), (4, .month))

let date6 = Date.beforeNow(difference: [(1, .minute), (2, .hour), (3, .day), (4, .month)])

let date7 = currentDate - (1, .day)

currentDate -= Date.Component(value: 1, type: .day)

More

• Get components (hours, months, days...) from date
• Compare days by components
• Convert date to formated string date