Convert list of AppleScript strings to a Swift array

Question

I have a complicated AppleScript that returns a list of strings that I need to access from Swift. I've boiled it down to a simple example and I just can't figure out how to map the AppleScript strings to an array of Swift strings.

let listOfStringsScript = """
                          set listOfStrings to { "one", "two", "three" }
                          """

 if let scriptObject = NSAppleScript(source: listOfStringsScript) {
    var errorDict: NSDictionary? = nil
    let resultDescriptor = scriptObject.executeAndReturnError(&errorDict)

    if errorDict == nil {
      // TODO: convert the resultDescriptor (NSAppleEventDescriptor) into an array of strings
      print(resultDescriptor)
      // OUTPUT: <NSAppleEventDescriptor: [ 'utxt'("one"), 'utxt'("two"), 'utxt'("three") ]>
    }
}

Just iterate thru the NSAppleEventDescriptor and pull out the strings one by one and append them to an array? — matt
– matt, Commented Apr 6, 2019 at 17:57
@matt That is what I did (I updated the question). I didn't initially know you could iterate through the descriptor. — RobertJoseph
– RobertJoseph, Commented Apr 6, 2019 at 18:01
developer.apple.com/documentation/foundation/… Just a matter of consulting the docs really :) — matt
– matt, Commented Apr 6, 2019 at 18:42
Is the script part of your app? (As opposed to user-supplied.) If so, you’ll find it a lot simpler to call AppleScript directly from Swift via the AppleScript-ObjC bridge. — foo
– foo, Commented Apr 7, 2019 at 7:32

RobertJoseph · Accepted Answer · 2019-04-07 12:11:32Z

3

Answer with help from @Alexander and @MartinR:

extension NSAppleEventDescriptor {

  func toStringArray() -> [String] {
    guard let listDescriptor = self.coerce(toDescriptorType: typeAEList) else {
      return []
    }

    return (0..<listDescriptor.numberOfItems)
      .compactMap { listDescriptor.atIndex($0 + 1)?.stringValue }
  }

}

...

let resultDescriptor = scriptObject.executeAndReturnError(&errorDict)
let subjectLines = resultDescriptor.toStringArray()

edited Apr 7, 2019 at 12:11

answered Apr 6, 2019 at 18:05

RobertJoseph

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3 Comments

rmaddy Over a year ago

I would combine the 2 if statements inside the loop to just if let s = listDescriptor.atIndex(i)?.stringValue {.

Martin R Over a year ago

Note that 1...listDescriptor.numberOfItems crashes for an empty array. Suggestion: (0..<listDescriptor.numberOfItems).compactMap { listDescriptor.atIndex($0+1)?.stringValue }

Alexander Over a year ago

@MartinR Good catch

tyirvine · Accepted Answer · 2021-04-14 05:39:08Z

1

An alternative is to gather the Apple Script result as lines of text separated by line breaks and then parse the string in Swift.

So break up the Apple Script result using

set AppleScript's text item delimiters to linefeed

Then simply parse

let selectedItems = scriptExecuted.stringValue!
let selectedItemsFiltered = selectedItems.components(separatedBy: .newlines)

.components returns a string array

answered Apr 14, 2021 at 5:39

tyirvine

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