Iterate file names in iOS documents directory.

filenames.swift

// Get documents directory
let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
let documentsDirectory = paths[0]

// Create enumerator
let fileManager = NSFileManager.defaultManager()
let enumerator:NSDirectoryEnumerator = fileManager.enumeratorAtPath(documentsDirectory as String)!

// Iterate files
while let element = enumerator.nextObject() as? String {
    print(element)
    if element.hasSuffix("jpg") { // Check extension
        print("jpg file")
    }
}