protocol SequenceType A type that can be iterated with a for...in loop. SequenceType makes no requirement on conforming types regarding whether they will be destructively "consumed" by iteration. To ensure non-destructive iteration, constrain your sequence to CollectionType. Inheritance _SequenceType, _Sequence_Type View Protocol Hierarchy → Associated Types Generator : GeneratorType A type that provides the sequence's iteration interface and encapsulates its iteration state. Import import Swift Instance Methods func generate() Required Return a generator over the elements of this sequence. Complexity: O(1) Declaration func generate() -> Generator Declared In SequenceType, _Sequence_Type