The indices that are valid for subscripting the collection, in ascending order.
- Xcode 7.1+
- Swift Standard Library
indices property can hold a strong reference to the collection itself, causing the collection to be nonuniquely referenced. If you mutate the collection while iterating over its indices, a strong reference can result in an unexpected copy of the collection. To avoid the unexpected copy, use the
index(after:) method starting with
start to produce indices instead.