Prior to Swift 4 I used the code below to join an array of strings into a single string:
let array = ["Andrew", "Ben", "John", "Paul", "Peter", "Laura"]
let joined = array.joined(separator: ", ")
//output:- "Andrew, Ben, John, Paul, Peter, Laura"
But now in Swift 4 and Xcode 9 is showing one of the following errors:
Ambiguous reference to member 'joined()'
Value of type 'TYPE' has no member 'join'
How can I join all elements of an array? Was the syntax changed in Swift 4?
That's a typical example where pseudo-code in the question is misleading and doesn't reproduce the error.
The error occurs because you are using flatMap. Since the array is a non-optional single-level array of Int just use map and don't use the describing initializer:
func getNumbers(array : [Int]) -> String {
let stringArray = array.map( String.init )
return stringArray.joined(separator: ",")
}
The ambiguity is that flatMap applied to an non-optional sequence has a different meaning:
From the documentation
let numbers = [1, 2, 3, 4] let mapped = numbers.map { Array(count: $0, repeatedValue: $0) } // [[1], [2, 2], [3, 3, 3], [4, 4, 4, 4]] let flatMapped = numbers.flatMap { Array(count: $0, repeatedValue: $0) } // [1, 2, 2, 3, 3, 3, 4, 4, 4, 4]In fact,
s.flatMap(transform)is equivalent toArray(s.map(transform).joined()).
flatMap? Could u describe what would you like to achive ?String(describing:)is almost never what you want (even if the compiler suggests it as a Fix-it).