Avoid many if conditions - ios

Question

i have 6 strings (text,year,age,....) i want to filter array based on them ... i want to check before if the string is empty or not .. if not empty then added to the if condition as an && .. but how to do something like this without the need to write many if conditions on each string with each other string ?
i want to avoid doing something like this:
if self.searchtext != "" && self.qualification != ""{
}else if self.searchtext != "" && self.qualification != "" && self.gender != ""{
}else if self.searchtext != "" && self.qualification != "" && self.gender != "" && self.year != ""{
}else if self.searchtext != "" && self.qualification != "" && self.gender != "" && self.year != "" && self.major != ""{
}
....
How to do this?
if self.searchtext != ""{
if user.name.contains(find: self.searchtext) || user.mobile.contains(find: self.searchtext) || user.email.contains(find: self.searchtext){
DispatchQueue.main.async {
self.phones.append(user.mobile)
self.names.append(user.name)
}
}
}else if self.qualification != ""{
if user.qualification.contains(find: self.qualification){
DispatchQueue.main.async {
self.phones.append(user.mobile)
self.names.append(user.name)
}
}
}else if self.gender != ""{
if user.gender.contains(find: self.gender){
DispatchQueue.main.async {
self.phones.append(user.mobile)
self.names.append(user.name)
}
}
}else if self.year != ""{
if user.graduateYear.contains(find: self.year){
DispatchQueue.main.async {
self.phones.append(user.mobile)
self.names.append(user.name)
}
}
}else if self.major != ""{
if user.specialization.contains(find: self.major){
DispatchQueue.main.async {
self.phones.append(user.mobile)
self.names.append(user.name)
}
}
}else if self.city != ""{
if user.city.contains(find: self.city){
DispatchQueue.main.async {
self.phones.append(user.mobile)
self.names.append(user.name)
}
}
}
}
This is what i have working .. but this works as an OR when i want it to be like AND for all none empty strings

Answer 1

Here's a paragraph copied from LinkedIn's style guide
Using guard Statements
3.11.1 In general, we prefer to use an "early return" strategy where applicable as opposed to nesting code in if statements. Using guard statements for this use-case is often helpful and can improve the readability of the code.
// PREFERRED
func eatDoughnut(at index: Int) {
guard index >= 0 && index < doughnuts.count else {
// return early because the index is out of bounds
return
}
let doughnut = doughnuts[index]
eat(doughnut)
}
// NOT PREFERRED
func eatDoughnut(at index: Int) {
if index >= 0 && index < doughnuts.count {
let doughnut = doughnuts[index]
eat(doughnut)
}
}
It's what I personally do, and it's a good convention to avoid nested if's.
In your case, you can do a couple of things. First and foremost, use .isEmpty instead of comparing the string to an empty string (""). If your only intent is to check if all your strings are empty, you can accomplish that like this:
let strings = [searchtext, qualification, ...]
guard strings.filter({ $0.isEmpty }).count == 0 else {
return
}
// Code that only works if all fields have values

Answer 2

We can certainly simplify things a lot.
I would start by wrapping search criteria into an object:
struct UserSearchCriteria {
var searchText = ""
var gender = ""
var qualification = ""
...
init() {}
}
Then you can use one variable instead of your X variables:
var searchCriteria = UserSearchCriteria()
then you can add a simple matching method:
extension UserSearchCriteria {
func matchesUser(_ user: User) -> Bool {
if !searchText.isEmpty && [user.name, user.mobile, user.email].contains(where: { $0.contains(find: searchText) }) {
return true
}
if !qualification.isEmpty && user.qualification.contains(find: qualification) {
return true
}
...
return false
}
}
Then your big condition is reduced to:
if self.searchCriteria.matches(user) {
DispatchQueue.main.async {
self.phones.append(user.mobile)
self.names.append(user.name)
}
}
You cannot really avoid the conditions, but you can simplify them and organize them better, without duplicating code.
It seems you want to match all search conditions then I would change the matching method to:
func matchesUser(_ user: User) -> Bool {
if !searchText.isEmpty && ![user.name, user.mobile, user.email].contains(where: { $0.contains(find: searchText) }) {
return false
}
if !qualification.isEmpty && !user.qualification.contains(find: qualification) {
return false
}
...
return true
}
(note the double negation - contains condition negated and returning false).

Answer 3

You can use Guard statement to Early exit a scope .
A guard statement is used to transfer program control out of a scope
if one or more conditions aren’t met.
This will pass only if all fields are not empty.
guard self.searchtext != "", self.qualification != "", self.gender != "", self.year != "", self.major != "" else { return }
Update:
guard let searchText = self.searchtext, !searchText.isEmpty else { return }
// do something with `searchText`. Here the above conditions will be true.
OR you can use if-let
if let searchText = self.searchtext, !searchText.isEmpty {
// do with `searchText`(non-optional).
} else {
// conditions failed.
}
If you are trying to filter your array, you can simply use array.filter
let filteredUsers = usersArray.filter {
let shouldIAddThisElement = $0.name.contains(searchText) // Do your logic here
return shouldIAddThisElement
}

Answer 4

Swift includes guard statement. The lines after the guard statement will only be executed if the guard condition is true. Like an if/else statement, the else clause runs if the condition is false.
guard condition else {
// false: execute some code
}
// true: execute some code
For your case:
guard self.searchtext && self.qualification && self.gender && self.year && self.major else { return }
// execute some code
The return statement will exit the function or method.
More information can be found in the documentation on "Early Exit" Section:
https://docs.swift.org/swift-book/LanguageGuide/ControlFlow.html