Extension for swift arrays to intersperse elements

IntersperseElement.swift

extension Array {
    func interspersing(_ element: Element) -> Array {
        var newArray: [Element] = []
        for (index, item) in self.enumerated() {
            newArray.append(item)
            if index < self.count - 1 {
                newArray.append(element)
            }
        }
        return newArray
    }
}

Useful idiom! Here's an alternative implementation:

func interspersing(_ element: Element) -> Array {
  flatMap { [$0, element] }.dropLast()
}

Yes, flatMap implementation is definately more elegant.

@Arrrlex wins for elegance. Here is one for performance sticklers.

extension Array {
    func interspersing(_ element: Element) -> Array {
        var newArray: [Element] = []
        guard !isEmpty else {
            return newArray
        }
        newArray.reserveCapacity(2 * count - 1)
        
        var i = startIndex
        let beforeEnd = index(before: endIndex)
        
        while i != beforeEnd {
            newArray.append(self[i])
            newArray.append(element)
            formIndex(after: &i)
        }
        newArray.append(self[i])
        return newArray
    }
}

@Arrrlex wins for elegance. Here is one for performance sticklers.

extension Array {
    func interspersing(_ element: Element) -> Array {
        var newArray: [Element] = []
        guard !isEmpty else {
            return newArray
        }
        newArray.reserveCapacity(2 * count - 1)
        
        var i = startIndex
        let beforeEnd = index(before: endIndex)
        
        while i != beforeEnd {
            newArray.append(self[i])
            newArray.append(element)
            formIndex(after: &i)
        }
        newArray.append(self[i])
        return newArray
    }
}

Awesome thanks @justinmeiners