If you want loop through json["items"] array, try:
for (key, subJson) in json["items"] {
if let title = subJson["title"].string {
println(title)
}
}
As for the second method, .arrayValue returns non Optional array, you should use .array instead:
if let items = json["items"].array {
for item in items {
if let title = item["title"].string {
println(title)
}
}
}