Another example about binarysearch HOT 3 OPEN

var myArray = ["a", "b", "d", "e"]
let newElement = "c"
if let index = myArray.index(where: { $0 > newElement }) {
    myArray.insert(newElement, at: index)
}

 extension Collection {
    func insertionIndex(of element: Self.Iterator.Element,
                        using areInIncreasingOrder: (Self.Iterator.Element, Self.Iterator.Element) -> Bool) -> Index {
        return index(where: { !areInIncreasingOrder($0, element) }) ?? endIndex
    }
}
var myArray = ["a", "b", "d", "e"]
let newElement = "c"
let index = myArray.insertionIndex(of: newElement, using: <)
myArray.insert(newElement, at: index)

extension RandomAccessCollection where Element : Comparable {
    func insertionIndex(of value: Element) -> Index {
        var slice : SubSequence = self[...]

        while !slice.isEmpty {
            let middle = slice.index(slice.startIndex, offsetBy: slice.count / 2)
            if value < slice[middle] {
                slice = slice[..<middle]
            } else {
                slice = slice[index(after: middle)...]
            }
        }
        return slice.startIndex
    }
}

extension RandomAccessCollection {
    /// Finds such index N that predicate is true for all elements up to
    /// but not including the index N, and is false for all elements
    /// starting with index N.
    /// Behavior is undefined if there is no such N.
    func binarySearch(predicate: (Element) -> Bool) -> Index {
        var low = startIndex
        var high = endIndex
        while low != high {
            let mid = index(low, offsetBy: distance(from: low, to: high)/2)
            if predicate(self[mid]) {
                low = index(after: mid)
            } else {
                high = mid
            }
        }
        return low
    }
}
Example usage:

(0 ..< 778).binarySearch { $0 < 145 } // 145