Filter results, slow performance Swift

Question

Swift question... I'm making a babyname app and trying to filter the results as chosen by the user. I managed to get it working, but it takes a while for the results to get filtered. I mean like 2-3 seconds.

Here is what I wrote :

func apply(list: [String]) -> [String] {
        let allSavedSettings = settings.all

        var newList = list
        
        if let short = allSavedSettings["short"] as? Bool {
            if !short {
                print("filter short")
                newList = newList.filter({$0.count > 4})
            }
        }
        if let long = allSavedSettings["long"] as? Bool {
            if !long {
                print("filter long")

                newList = newList.filter({$0.count < 5})
            }
        }
        if let dutch = allSavedSettings["dutch"] as? Bool {
            if !dutch {
                print("filter dutch")

                newList = newList.filter({!dutchboy.contains($0)})
                newList = newList.filter({!dutchgirl.contains($0)})
            }
        }
        if let english = allSavedSettings["english"] as? Bool {
            if !english {
                print("filter english")

                newList = newList.filter({!englishboy.contains($0)})
                newList = newList.filter({!englishgirl.contains($0)})
                
            }
        }
        if let arabic = allSavedSettings["arabic"] as? Bool {
            if !arabic {
                print("filter arabic")

                newList = newList.filter({!arabicboy.contains($0)})
                newList = newList.filter({!arabicgirl.contains($0)})
                
            }
        }
        if let hebrew = allSavedSettings["hebrew"] as? Bool {
            if !hebrew {
                print("filter hebrew")

                newList = newList.filter({!hebrewboy.contains($0)})
                newList = newList.filter({!hebrewgirl.contains($0)})
                
            }
        }
        if let latin = allSavedSettings["latin"] as? Bool {
            if !latin {
                print("filter latin")

                newList = newList.filter({!latinboy.contains($0)})
                newList = newList.filter({!latingirl.contains($0)})
                
            }
        }
        if let chinese = allSavedSettings["chinese"] as? Bool {
            if !chinese {
                print("filter chinese")

                newList = newList.filter({!chineseboy.contains($0)})
                newList = newList.filter({!chinesegirl.contains($0)})
                
            }
        }
        if let scandinavian = allSavedSettings["scandinavian"] as? Bool {
            if !scandinavian {
                print("filter scandinavian")

                newList = newList.filter({!scandinavianboy.contains($0)})
                newList = newList.filter({!scandinaviangirl.contains($0)})
                
            }
        }
        if let spanish = allSavedSettings["spanish"] as? Bool {
            if !spanish {
                print("filter spanish")

                newList = newList.filter({!spanishboy.contains($0)})
                newList = newList.filter({!spanishgirl.contains($0)})
                
            }
        }
        
        return newList
    }

So I save the users preferences as a Boolean value in an array called "allSavedSettings" with userdefaults. Whenever a setting is false it will filter the result from the complete list of names.

Is there something else I should use, to speed things up? The list is about 5000 names.

Thanks in advance.

Patrick

Answer 1

I'd use sets wherever possible since hashing is faster than iterating over an array multiple times and it eliminates duplicates. You do not need to convert your main list to a set as that would add additional cycles.

Something like this should speed things up.

var doNotInclude = Set<String>()
        
if allSavedSettings["english"] == false {
    doNotInclude.formUnion(Set(englishBoy + englishGirl))
}

if allSavedSettings["dutch"] == false {
    doNotInclude.formUnion(Set(dutchBoy + dutchGirl))
}

if allSavedSettings["arabic"] == false {
    doNotInclude.formUnion(Set(arabicBoy + arabicGirl))
}

let result = list.filter { !doNotInclude.contains($0) }