fun.swift

Start with an array of optionals and flat whack the heck out of 'em.

flatMap

let results = arrayOfOptionals.flatMap({$0})

for case

var results = [String]()
for case let value? in arrayOfOptionals {results.append(value)}

flatMap with (ugly) forced unwrap

let results = arrayOfOptionals.flatMap{$0 == nil ? [] : [$0!]}

map and append

var results = [String]()
arrayOfOptionals.map({
    (optional : String?) -> Void in 
    if case let value? = optional {
        results.append(value)}
})

for / guard

results = [String]()
for optional in arrayOfOptionals {
    guard let unwrapped = optional else {continue}
    results.append(unwrapped)
}

or worse:

results = [String]()
for optional in arrayOfOptionals {
    do {
        guard let value = optional else {throw NSError(domain:"", code:0, userInfo:nil)}
        results += [value]
    } catch {}
}

flatmap / map

// Thanks eridius
results = arrayOfOptionals.flatMap({ $0.map({[$0]}) ?? [] })

reduce / combine

// Thanks eridius 
results = arrayOfOptionals.reduce([], combine: { $1 == nil ? $0 : $0 + [$1!] })

split / flat / flat

results = split(arrayOfOptionals, isSeparator: {$0 == nil}).flatMap({$0}).flatMap({$0})

filter / map

results = arrayOfOptionals.filter({$0 !=  nil}).map{$0!}

recurse

func squeezle(var arrayOfOptionals : [String?]) -> [String] {
    if arrayOfOptionals.isEmpty {return []}
    if let last = arrayOfOptionals.removeLast() {
        return squeezle(arrayOfOptionals) + [last]
    } else {return squeezle(arrayOfOptionals)}
}
results = squeezle(arrayOfOptionals)