In Swift, there are several ways to work with date formatting, such as DateComponentsFormatter and RelativeDateTimeFormatter.
DateComponentsFormatter
- Formats a time interval (duration) between two points in time.
- It doesn’t know whether it’s past or future, only the length of time.
- Example outputs:
2d,1 hour, 5 minutes,3h 15m - Use it for: durations, timers, countdowns, video lengths, etc.
RelativeDateTimeFormatter
- Formats a date relative to another date, automatically handling past or future.
- Adds natural language like “ago” or “in”.
- Example outputs:
2 days ago,in 3 hours,yesterday,tomorrow - Use it for: human-readable time expressions like “5m ago” or “in 2d”.
Quick Comparison
| Purpose | Formatter | Example |
|---|---|---|
| Duration (no direction) | DateComponentsFormatter | 2d, 3h 15m |
| Relative time (with context) | RelativeDateTimeFormatter | 2 days ago, in 3 hours |
Example of usage
DateComponentsFormatter:
private var abbreviatedFormatter: DateComponentsFormatter { let formatter = DateComponentsFormatter() formatter.allowedUnits = [.minute, .hour, .day] formatter.unitsStyle = .abbreviated formatter.maximumUnitCount = 1 return formatter } func asAbbreviatedString() -> String { let from = Date().timeIntervalSince(self) return abbreviatedFormatter.string(from: from) ?? "" } RelativeDateTimeFormatter:
private var shortFormatter: RelativeDateTimeFormatter { let formatter = RelativeDateTimeFormatter() formatter.unitsStyle = .full return formatter } func asShortString() -> String { return shortFormatter.localizedString(for: self, relativeTo: Date()) } Pro tip
Create an extension and add these shorthand functions to it.
extension Date { private var abbreviatedFormatter: DateComponentsFormatter { let formatter = DateComponentsFormatter() formatter.allowedUnits = [.minute, .hour, .day] formatter.unitsStyle = .abbreviated formatter.maximumUnitCount = 1 return formatter } private var shortFormatter: RelativeDateTimeFormatter { let formatter = RelativeDateTimeFormatter() formatter.unitsStyle = .full return formatter } func asAbbreviatedString() -> String { let from = Date().timeIntervalSince(self) return abbreviatedFormatter.string(from: from) ?? "" } func asShortString() -> String { return shortFormatter.localizedString(for: self, relativeTo: Date()) } } 
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