Download the app from the iTunes store for free here
#NOTE: The code is open source NOT the design or images :) Thanks.
Open Source Weather App created with Swift and powered by Forecast.io
https://developer.forecast.io
Once you have your API key open up the ViewController.swift file and jump down to line 80.
private let apiKey = "YOUR API KEY" // https://developer.forecast.io replace the text "YOUR API KEY" with the API Key from forecast.io and run the app.