enumerate function in Swift

Question

I am trying to iterate over an array of strings, using the global enumerate function in Swift.

It looks like this:

let fontNames = UIFont.fontNamesForFamilyName(familyName)

 for (index, value) in enumerate(fontNames) {
    // Do something here     
  }

But Xcode complains with an error saying

Cannot convert the expression's type 'EnumerateGenerator' to type '$T1'

Answer 1

fontNamesForFamilyName() returns AnyObject[]!, which can't be directly enumerated. You have explicitly type your fontNames array.

let fontNames: Array = UIFont.fontNamesForFamilyName(familyName)
for (index, value : AnyObject) in enumerate(fontNames) {
    println(value)
}

And as @Van Du Tran pointed out in the comments below, the syntax for enumerate has changed in Swift 2. Now you can use the following.

let fontNames: Array = UIFont.fontNamesForFamilyName(familyName)
for (index, value) in fontNames.enumerate() {
    print(value)
}

It's also worth noting that since fontNamesForFamilyName now uses an Objective C generic type, it returns [String] so no conversion from AnyObject is needed.

Answer 2

I might disagree with @0x7fffffff's answer. I think the issue is not that AnyObject[] can't be directly enumerated, but rather that it's returned as an implicitly unwrapped optional.

As a test:

    let myStuff: AnyObject[] = ["Neat"]
    for (index, value) in enumerate(myStuff) { // < No issues
        print("\(value)")
    }

    let myStuff2: AnyObject[]! = ["Neat"]
    for (index, value) in enumerate(myStuff2) { // < Compiler error
        print("\(value)")
    }

I think a better solution is to unwrap the optional in your enumerate() function:

for (index, value) in enumerate(fontNames!) { // < Note the bang
...