How to get the root cause when createFile fails? - ios

Question

Trying to create a file using createFile API on iOS.
createFile(path, data, attr)
Document says,
Return Value:
true if the operation was successful or if the item already exists, otherwise false.
I wonder if the operation was not successful, how can I get the exact cause of the failure?. Expected some API like,
createFile(path, data, attr, &error)

Answer 1

Use Data.write(to:options:) instead, it throws.
I use FileManager.default.createDirectory to create folders. I create Data that I want to write, and then I use Data.write to save it to disk.
var docDir = URL()
do {
docDir = try FileManager.default.url(
for: .documentDirectory,
in: .userDomainMask,
appropriateFor: nil,
create: true
)
} catch {
fatalError("\(error)")
}
let subDir = docDir.appendPathComponents("mySubDir")
do {
try FileManager.default.createDirectory(
at: subdir,
withIntermediateDirectories: true,
attributes: nil
)
} catch {
if (error as NSError).code == 516 {
// "The file “x” couldn’t be saved in the folder “y” because a file with the same name already exists."
// This is OK.
} else {
fatalError("\(error)")
}
}
let filePath = subdir.appendingPathComponent("yourFileName")
let object:Codable = Whatever()
let data = try! JSONEncoder().encode(object)
do {
try data.write(to: filePath)
} catch {
fatalError("\(error)")
}
I do not know why Apple devs chose FileManager.createFile to be different. It seems strange to me.