Better way to write this if condition with a force-unwrap? - swift

Question

Given these variables:
let urls: [URL] = []
let defaultURL = urls.first?
It's straightforward to write a conditional statement to do something based on whether there's a file or not.
if let url = defaultURL, FileManager.default.fileExists(atPath: url.path) {
// Do something
} else {
// Do something else
}
But if you don't need to do something in the first case, I can't come up with a better way to write the condition than this:
if defaultURL == nil || !FileManager.default.fileExists(atPath: defaultURL!.path) {
// Do something
}
Is there a better way to write this? I don't like the force-unwrap, but at the same time, it feels safe to write that.

Answer 1

There are many ways to solve this situation.
The simplest one is to extract the condition into a separate function/closure and check
func fileExists(defaultUrl: URL?) -> Bool {
guard let defaultUrl = defaultUrl else { return false }
return FileManager.default.fileExists(atPath: defaultUrl.path)
}
The same can be done using a variable:
let fileExists: Bool
if let defaultUrl = defaultUrl {
fileExists = FileManager.default.fileExists(atPath: defaultUrl.path)
} else {
fileExists = false
}
Or, you can use Optional.map:
let fileExists = defaultUrl.map { FileManager.default.fileExists(atPath: $0.path) } ?? false

Answer 2

You can make it more clear and readable by making a variable that makes if condition an english sentence i.e.
let fileNotExists = !(defaultUrl.map{ FileManager.default.fileExists(atPath: $0.path)} ?? false)
if fileNotExists {
//Do your stuff
}