Filter array that contains optional - SearchBar - ios

Question

just a bit of hindsight for you to understand my problem. I am currently coding an iOS app for events where I have a GuestList CoreData saved on device.
On viewDidLoad, it will fetch the coredata object and place it into an array of [GuestDetails]
Now the Guestdetail object struct is as follows:
private(set) public var guestFirstName: String
private(set) public var guestLastName: String?
private(set) public var guestEmail: String?
private(set) public var guestPhone: String?
private(set) public var guestUUID: UUID
private(set) public var guestBarcode: String?
private(set) public var guestCheckedIn: Bool
Such that only first name, UUID and checkinStatus are compulsory. I have already set up adding by JSON but now my issue is on my GuestListViewController, I have a searchbar
I am using the following code and array to make sure I can filter.
I have another array that is called
searchResultArray = [GuestDetails]()
So essentially I would copy all my guest details to searchResultArray and that is the one that the tableView is getting its sources from.
Now as part of the search, I used this code which I found on appcoda
searchResultArray = guestData.filter({guestData -> Bool in
(guestData.guestFirstName.lowercased().contains(searchText.lowercased())) ||
(guestData.guestLastName?.lowercased().contains(searchText.lowercased()))! ||
(guestData.guestBarcode?.contains(searchText))!
})
The issue is that my app is crashing, if I only search by first name it will not crash since those are force unwrapped nicely, but if I add the code to search lastName or Barcode, it will crash. I understand that it is probably because of explicitly unwrapped but xcode would not let me NOT unwrap it.
I have tried using map (which does not help, unless i am not familiar enough with it),
I have tried .compact (but I could not get it to work as i am not sure how it can access the inside of an GuestDetail object to remove nils)
The issue is the array of [GuestDetails] itself will not contain null some details inside a GuestDetails object might, hence causing it to crash.
My question is, how do I get it to search by firstname(already possible), lastname and barcode?
Thanks and I hope the question was elaborate enough.

Answer 1

I would avoid using forced unwrapping like so:
searchResultArray = guestData.filter({guestData -> Bool in
let searchLowercased = searchText.lowercased()
if guestData.guestFirstName.lowercased().contains(searchLowercased) {
return true
}
if let guestLastName = guestData.guestLastName, guestLastName.lowercased().contains(searchLowercased) {
return true
}
if let guestBarcode = guestData.guestBarcode, guestBarcode.lowercased().contains(searchLowercased) {
return true
}
return false
})
Answering your question from comments: You don't have to use ? operator on optionals because we use Optional Binding if let syntax. So for example:
if let guestLastName = guestData.guestLastName if guestData.guestLastName is nil than we will just jump out of this if statement. then you see , in the if statement, we will go pass this comma only if guestData.guestLastName is not nil, that is why we can use the guestLastName variable that is unwrapped String and is no longer optional String?, we than proceed to check if search term matches the guestLastName and return true.
Please read: if let , if var, guard let,guard var and defer statements in swift
It would be even better if you happen to add another property to your Data and avoid doing all this if else you can do something like:
searchResultArray = guestData.filter({guestData -> Bool in
let searchLowercased = searchText.lowercased()
let matches:[String?] = [guestData.guestFirstName, guestData.guestLastName, guestData.guestBarcode]
let nonNilElements = matches.compactMap { $0 }
for element in nonNilElements {
if element.lowercased().contains(searchLowercased) {
return true
}
}
return false
})

Answer 2

It's an interesting little problem, so let's generalize it. Here's our test data, comparable to your array of GuestDetails:
struct S {
var s1 : String
var s2 : String?
var s3 : String?
}
var array = [S]()
array.append(S(s1: "test", s2: "yo", s3: "ha"))
array.append(S(s1: "test", s2: nil, s3: nil))
array.append(S(s1: "Howdy", s2: "Bonjour", s3: "Hello"))
let target = "hello"
Some S properties are Optional, others are not.
So the problem is: Filter array down to only those elements where any S property contains our target string, using case insensitive comparison.
We can do that in one statement:
let filteredArray = array.filter {
[$0.s1,$0.s2,$0.s3].compactMap {$0}
.map {$0.localizedCaseInsensitiveContains(target)}
.contains(true)
}
It's not quite as efficient as what #Ladislav wrote, because we keep looping inside map even after we've found our string. But the inefficiency is probably not significant.