swift temporary directory
func createTempDirectory() -> String? {
let tempDirectoryTemplate = NSTemporaryDirectory().stringByAppendingPathComponent("XXXXX")
let fileManager = NSFileManager.defaultManager()
var err: NSErrorPointer = nil
if fileManager.createDirectoryAtPath(tempDirectoryTemplate, withIntermediateDirectories: true, attributes: nil, error: err) {
return tempDirectoryTemplate
} else {
return nil
}
}