Depending on the accuracy you want either add 7 * 24 * 60 to your timestamp as suggested in the comments is one way.
Note you could also create a date from the timestamp and use the appropriate date functions as described here: How do I add 1 day to an NSDate?
if your loginUpdateDate is a Swift Date, just use the code in the link. Otherwise use the timestamp (the 10 digit int) to create a date:
let lastLoginDate = Date(timeIntervalSince1970: lastLoginUpdate)
var dayComponent = DateComponents()
dayComponent.day = 1 // For removing one day (yesterday): -1
let theCalendar = Calendar.current
let nextAllowedDate = theCalendar.date(byAdding: dayComponent, to: lastLoginDate)
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