Swift: How to expand a tilde in a path String

问题:

How can I expand a path String with a tilde in Swift? I have a string like "~/Desktop" and I'd like to use this path with the NSFileManager methods, which requires the tilde to be expanded to "/Users/<myuser>/Desktop".

(This question with a clear problem statement doesn't exist yet, this should be easily findable. Some similar but not satisfying questions are Can not make path to the file in Swift, Simple way to read local file using Swift?, Tilde-based Paths in Objective-C)

回答1:

Tilde expansion

Swift 1

"~/Desktop".stringByExpandingTildeInPath

Swift 2

NSString(string: "~/Desktop").stringByExpandingTildeInPath

Swift 3

NSString(string: "~/Desktop").expandingTildeInPath

Home Directory

Additionally you can get the home directory like this (returns a String/String?):

NSHomeDirectory()
NSHomeDirectoryForUser("<User>")

In Swift 3 and OS X 10.12 it's also possible to use this (returns a URL/URL?):

FileManager.default().homeDirectoryForCurrentUser
FileManager.default().homeDirectory(forUser: "<User>")

Edit: In Swift 3.1 this got changed to FileManager.default.homeDirectoryForCurrentUser

回答2:

Return string:

func expandingTildeInPath(_ path: String) -> String {
    return path.replacingOccurrences(of: "~", with: FileManager.default.homeDirectoryForCurrentUser.path)
}

Return URL:

func expandingTildeInPath(_ path: String) -> URL {
    return URL(fileURLWithPath: path.replacingOccurrences(of: "~", with: FileManager.default.homeDirectoryForCurrentUser.path))
}

If OS less than 10.12, replace

FileManager.default.homeDirectoryForCurrentUser

with

URL(fileURLWithPath: NSHomeDirectory()

回答3:

Here is a solution that does not depend on the NSString class and works with Swift 4:

func absURL ( _ path: String ) -> URL {
    guard path != "~" else {
        return FileManager.default.homeDirectoryForCurrentUser
    }
    guard path.hasPrefix("~/") else { return URL(fileURLWithPath: path)  }

    var relativePath = path
    relativePath.removeFirst(2)
    return URL(fileURLWithPath: relativePath,
        relativeTo: FileManager.default.homeDirectoryForCurrentUser
    )
}

func absPath ( _ path: String ) -> String {
    return absURL(path).path
}

Test code:

print("Path: \(absPath("~"))")
print("Path: \(absPath("/tmp/text.txt"))")
print("Path: \(absPath("~/Documents/text.txt"))")

The reason for splitting the code into two methods is that nowadays you rather want URLs when working with files and folders and not string paths (all new APIs use URLs for paths).

By the way, if you just want to know the absolute path of ~/Desktop or ~/Documents and similar folders, there's an even easier way for that:

let desktop = FileManager.default.urls(
    for: .desktopDirectory, in: .userDomainMask
)[0]
print("Desktop: \(desktop.path)")

let documents = FileManager.default.urls(
    for: .documentDirectory, in: .userDomainMask
)[0]
print("Documents: \(documents.path)")

回答4:

Swift 4 Extension

public extension String {

    public var expandingTildeInPath: String {
        return NSString(string: self).expandingTildeInPath
    }

}