Check if string is not nil or not empty using Swift 5

Question

So I want to utilize something that has the best performance, but also check for both nil and also not empty on strings.

Example: If the string is not nil, but also not empty, show showLinkButton.

So I was able to use this code:

if let website = item.website, !item.website.isEmpty {
    showLinkButton
}

Where I have a @ViewBuilder such as this:

@ViewBuilder private var showLinkButton: some View {
    Button(action: {
        self.isBrowsingWebsite = true
    }, label: {
        Image(systemName: "link")
            .resizable()
            .scaledToFit()
            .frame(height: 14)
            .fontWeight(.bold)
            .padding(5)
    })
    .foregroundColor(.secondary)
    .background(
        RoundedRectangle(cornerRadius: 5, style: .continuous)
            .fill(Color(.systemGray6))
    )
    .sheet(isPresented: $isBrowsingWebsite) {
        SafariViewWrapper(url: URL(string: item.website)!)
    }
}

Problem:
The problem is that I'm not really doing anything with let website, so I am getting the following errors:

Immutable value 'website' was never used; consider replacing with '_' or removing it && Replace 'let website' with '_'.

Questions:

If I utilize if _ = item.website, !item.website.isEmpty, will this hurt performance? Is there a better way to do it?
Since I will have multiple if statements, would if _ = ... have negative side effects being called 5+ times in the same View.

if let website = item.website, !item.website.isEmpty { should be if let website = item.website, !website.isEmpty {. Then you won't get the warning. — HangarRash
– HangarRash, Commented Dec 7, 2022 at 4:00

vacawama · Accepted Answer · 2022-12-07 04:01:03Z

2

Use optional chaining to call isEmpty and compare explicitly to false:

if item.website?.isEmpty == false {
    print("not nil and not empty")
}

Note:

If you want to check if a value is nil, just compare it to nil. Don't use if let unless you want to use the unwrapped value.

edited Dec 7, 2022 at 4:01

answered Dec 7, 2022 at 3:54

vacawama

155k32 gold badges283 silver badges315 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

theMap Over a year ago

I am getting this error Cannot use optional chaining on non-optional value of type 'String'. Could I utilize it without the optional ? - Nvm, I updated the var website: String?.

HangarRash Over a year ago

@theMap If website isn't optional then your whole question becomes irrelevant.

vacawama Over a year ago

A value can't be nil unless it is an optional. Why are you trying to test if it is nil if it isn't optional?

vacawama Over a year ago

If the value coming from the database can be nil, then the variable you are storing it in should be an optional.

theMap Over a year ago

Thanks for the explanation @vacawama, I will update the variable to handle optional.

Collectives™ on Stack Overflow

Check if string is not nil or not empty using Swift 5

1 Answer 1

5 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related