How to make struct a subscriptable in Swift 2? - arrays

Question

Within my struct I have the following:
subscript(index: Int) -> FileSystemObject {
var i: Int = 0
for a in contents! {
if (i == index) {
return a
}
i++
}
}
Where,
var contents: FileSystemObject = [FileSystemObject]?
But when,
let it: FileSystemObject = FileSystemObject()
And I write:
return it.contents![index]
I receive the error
Cannot subscript a value of type [FileSystemObject]
What am I doing wrong here?
Additionally, note that:
Changing each of the objects with the value
FileSystemObject
To,
[FileSystemObject]
Does not help.
EDIT 1:
This is the entirety of the code:
MainWindowController.swift
class MainWindowController: NSWindowController, NSOutlineViewDataSource, NSOutlineViewDelegate {
#IBOutlet weak var sourceView: NSOutlineView!
static var fileManager: NSFileManager = NSFileManager.defaultManager()
static var fileSystem: FileSystemObject = FileSystemObject(path: "/", fs: fileManager)
var outlineSource: OutlinePrep = OutlinePrep(fs: fileSystem)
override func windowDidLoad() {
super.windowDidLoad()
sourceView.setDataSource(self)
sourceView.setDelegate(self)
}
func outlineView(outlineView: NSOutlineView, child index: Int, ofItem item: AnyObject?) -> AnyObject {
guard let it = item as? OutlinePrep else {
return outlineSource.basePath
}
return it.data[index]
}
func outlineView(outlineView: NSOutlineView, isItemExpandable item: AnyObject) -> Bool {
// return (item == nil) ? YES : ([item numberOfChildren] != -1);
print(item)
guard let it = item as? OutlinePrep else {
return false
}
for (var i: Int = 0; i < it.data.count; i++) {
guard let _ = it.data[i].contents else {
return false
}
}
return true
}
func outlineView(outlineView: NSOutlineView, numberOfChildrenOfItem item: AnyObject?) -> Int {
guard let it = item as? OutlinePrep else {
return outlineSource.data.count
}
var i: Int = 0
for a in it.data {
guard let _ = a.contents else {
continue
}
i++
}
return i
}
}
FileSystem.swift
struct FileSystemObject {
let basePath: String
let name: String
var isDir = ObjCBool(false)
var contents: [FileSystemObject]?
init(path: String, fs: NSFileManager) {
basePath = path
let root: [String]
fs.fileExistsAtPath(path, isDirectory: &isDir)
if (isDir.boolValue) {
do {
root = try fs.contentsOfDirectoryAtPath(path)
}
catch {
root = ["Error"]
}
contents = []
for r in root {
contents!.append(FileSystemObject(path: (path + (r as String) + "/"), fs: fs))
}
}
name = path
}
subscript(index: Int) -> FileSystemObject {
get {
let error: FileSystemObject = FileSystemObject(path: "", fs: NSFileManager.defaultManager())
guard let _ = contents else {
return error
}
var i: Int = 0
for a in contents! {
if (i == index) {
return a
}
i++
}
return error
}
set {
}
}
}
Outline.swift
struct OutlinePrep {
var data: [FileSystemObject]
let basePath: String
private var cell: Int = -1
init (fs: FileSystemObject) {
data = fs.contents!
basePath = fs.basePath
}
mutating func outlineDelegate() -> String {
cell++
return data[cell].name
}
func testFunc(data: [FileSystemObject]) {
for (var i: Int = 0; i < data.count; i++) {
guard let d = data[i].contents else {
print(data[i].name)
continue
}
testFunc(d)
}
}
}
EDIT 2:
To clarify, I am inquiring as to how I might resolve the error, as all other provided code works as intended.

Answer 1

The error message is misleading. The problem becomes more apparent
if you split
return it.data[index]
into two separate statements:
func outlineView(outlineView: NSOutlineView, child index: Int, ofItem item: AnyObject?) -> AnyObject {
guard let it = item as? OutlinePrep else {
return outlineSource.basePath
}
let fso = it.data[index]
return fso // error: return expression of type 'FileSystemObject' does not conform to 'AnyObject'
}
The value of it.data[index] is a
FileSystemObject, which is a struct and therefore it
does not conform to AnyObject and cannot be the return value
of that method. If you want to return a FileSystemObject
then you have to define that as a class instead.

Answer 2

simplified ...
struct FileSystemObject {
var context: [FileSystemObject]?
init() {
context = []
// your init is called recursively, forever ...
let fso = FileSystemObject()
context?.append(fso)
}
}
let s = FileSystemObject()