read(fromAbsoluteOffset:into:retryOnInterrupt:)

Reads bytes at the specified offset into a buffer.

Declaration

func read(fromAbsoluteOffset offset: Int64, into buffer: UnsafeMutableRawBufferPointer, retryOnInterrupt: Bool = true) throws -> Int

Parameters

offset:
The file offset where reading begins.
buffer:
The region of memory to read into.
retryOnInterrupt:
Whether to retry the read operation if it throws Interrupted. The default is true. Pass false to try only once and throw an error upon interruption.

Mentioned in

Adopting Swift File Operations

Return Value

The number of bytes that were read.

Discussion

The doc://com.apple.documentation/documentation/swift/unsafemutablerawbufferpointer/count-95usp property of buffer determines the maximum number of bytes that are read into that buffer.

Unlike read(into:retryOnInterrupt:), this method leaves the file’s existing offset unchanged.

The corresponding C function is pread.