FB11186889: -[NSURL initFileURLWithPath:] returns nil when initialized with an empty string

[macmade]

• Date: 2022-08-10
• Resolution: Open
• Area: Foundation
• OS: macOS
• Type: Incorrect/Unexpected Behavior
• Keywords: foundation, url, nil, crash

Description

When initialized with an empty string using the fileURLWithPath, NSURL returns nil.
Unfortunately, the initializer is not marked as failable in Swift, leading to runtime crashes.

Consider the code below:

import Foundation

let url1 = URL( fileURLWithPath: "" )
let url2 = NSURL( fileURLWithPath: "" )

print( url1 )
print( url2 )

Here, both url1 and url2 are non-optional.
However, url2 will still be nil at runtime, leading to a crash in the last line, when trying to use the value.

Attached is a sample project demonstrating the issue.

Files

URL.zip