For an introduction and motivation into Embedded Swift, please see "A Vision for Embedded Swift", a Swift Evolution document highlighting the main goals and approaches.
| Language Feature | Currently Supported In Embedded Swift |
|---|---|
| Anything not listed below | Yes |
| Library Evolution (resilience) | No, intentionally unsupported long-term |
| Objective-C interoperability | No, intentionally unsupported long-term |
| Non-WMO builds | No, intentionally unsupported long-term (WMO should be used) |
| Existentials (values of protocol types) | Only class-bound existentials (for protocols derived from AnyObject) are supported |
| Any | No, currently disallowed |
| AnyObject | Yes |
| Metatypes | No, currently only allowed as unused arguments (type hints) |
| Untyped throwing | No, intentionally unsupported long-term (typed throwing should be used instead) |
| Weak references, unowned references | No |
| Non-final generic class methods | No, intentionally unsupported long-term |
| Parameter packs (variadic generics) | No, not yet supported |
This status table describes which of the following standard library features can be used in Embedded Swift:
| Swift Standard Library Feature | Currently Supported In Embedded Swift? |
|---|---|
| Array (dynamic heap-allocated container) | Yes |
| Array slices | Yes |
| assert, precondition, fatalError | Partial, only StaticStrings can be used as a failure message |
| Bool, Integer types, Float types | Yes |
| Codable, Encodable, Decodable | No |
| Collection + related protocols | Yes |
| Collection algorithms (sort, reverse) | Yes |
| CustomStringConvertible, CustomDebugStringConvertible | Yes, except those that require reflection (e.g. Array's .description) |
| Dictionary (dynamic heap-allocated container) | Yes |
| Floating-point conversion to string | No |
| Floating-point parsing | No |
| FixedWidthInteger + related protocols | Yes |
| Hashable, Equatable, Comparable protocols | Yes |
| InputStream, OutputStream | No |
| Integer conversion to string | Yes |
| Integer parsing | No |
| KeyPaths | Partial (only compile-time constant key paths to stored properties supported, only usable in MemoryLayout and UnsafePointer APIs) |
| Lazy collections | No |
| ManagedBuffer | Yes |
| Mirror (runtime reflection) | No, intentionally unsupported long-term |
| Objective-C bridging | No, intentionally unsupported long-term |
| Optional | Yes |
| print / debugPrint | Partial (only String, string interpolation, StaticStrings, integers, pointers and booleans) |
| Range, ClosedRange, Stride | Yes |
| Result | Yes |
| Set (dynamic heap-allocated container) | Yes |
| SIMD types | Yes |
| StaticString | Yes |
| String (dynamic) | Yes |
| String interpolations | Partial (only strings, integers, booleans, and custom types that are CustomStringConvertible can be interpolated) |
| Unicode | Yes |
| Unsafe[Mutable][Raw][Buffer]Pointer | Yes |
| VarArgs | No |
This status table describes which of the following Swift features can be used in Embedded Swift:
| Swift Feature | Currently Supported In Embedded Swift? |
|---|---|
| Synchronization module | Partial (only Atomic types, no Mutex) |
| Swift Concurrency | Partial, experimental (basics of actors and tasks work in single-threaded concurrency mode) |
| C interop | Yes |
| C++ interop | Yes |
| ObjC interop | No, intentionally unsupported long-term |
| Library Evolution | No, intentionally unsupported long-term |