添加一个辅助函数作为Date的扩展，它检查特定日期组件的值是否相等

extension Date {
    func isValueOfComponent(_ component: Calendar.Component, equalTo date: Date) -> Bool {
        Calendar.current.component(component, from: self) == Calendar.current.component(component, from: date)
    }
}

然后比较

if example.date!.isValueOfComponent(.day, equalTo: Date())

能够考虑多个组件的更灵活的解决方案是

extension Date {
    func isDateEqual(to date: Date, matching components: Set<Calendar.Component>) -> Bool {
        Calendar.current.dateComponents(components, from: self) == Calendar.current.dateComponents(components, from: date)
    }
}

并利用它

if example.date!.isDateEqual(to: Date(), matching: [.month, .day])