https://stackoverflow.com/questions/30973044/how-to-restrict-uitextfield-to-take-only-numbers-in-swift

https://stackoverflow.com/questions/33987442/how-to-create-a-custom-pop-up-view-with-swift

https://stackoverflow.com/questions/30419087/swift-how-do-i-segue-from-viewcontroller-to-tabbarcontroller

https://stackoverflow.com/questions/24070450/how-to-get-the-current-time-as-datetime

https://stackoverflow.com/questions/26819423/show-uipickerview-text-field-is-selected-then-hide-after-selected

https://stackoverflow.com/questions/23149781/get-currently-selected-value-of-uipickerview

https://stackoverflow.com/questions/27135997/perform-segue-from-app-delegate-swift

https://stackoverflow.com/questions/30130441/cant-get-the-integer-from-core-data-atribute

https://stackoverflow.com/questions/11607024/how-to-load-different-view-controller-class-from-app-delegate-at-the-time-of-app

https://stackoverflow.com/questions/26545621/get-values-from-coredata-in-swift