Returns an initialized output stream for writing to a specified file.
- iOS 2.0+
- macOS 10.3+
- tvOS 9.0+
- watchOS 2.0+
The path to the file the output stream will write to.
YESif newly written data should be appended to any existing file contents, otherwise
An initialized output stream that can write to
The stream must be opened before it can be used.