Return Value 戻り値
The value returned from body, unless the sequence doesn’t support contiguous storage, in which case the method ignores body and returns nil.
Instance Method
インスタンスメソッド
with
withContiguousStorageIfAvailable(_:)
Executes a closure on the sequence’s contiguous storage.
Availability 有効性
- iOS 13.0+
- iPadOS 13.0+
- macOS 10.15+
- Mac Catalyst 13.0+
- tvOS 13.0+
- watchOS 6.0+
Technology
- Swift
UI
Declaration 宣言
func withContiguousStorageIfAvailable<R>(_ body: (UnsafeBufferPointer <Self.Element>) throws -> R) rethrows -> R?Parameters パラメータ
bodyA closure that receives an
Unsafeto the sequence’s contiguous storage.Buffer Pointer
Discussion 議論
This method calls body(buffer), where buffer is a pointer to the collection’s contiguous storage. If the contiguous storage doesn’t exist, the collection creates it. If the collection doesn’t support an internal representation in a form of contiguous storage, the method doesn’t call body — it immediately returns nil.
The optimizer can often eliminate bounds- and uniqueness-checking within an algorithm. When that fails, however, invoking the same algorithm on the buffer argument may let you trade safety for speed.
Successive calls to this method may provide a different pointer on each call. Don’t store buffer outside of this method.
A Collection that provides its own implementation of this method must provide contiguous storage to its elements in the same order as they appear in the collection. This guarantees that it’s possible to generate contiguous mutable storage to any of its subsequences by slicing buffer with a range formed from the distances to the subsequence’s start and end, respectively.