Widgets(Today Extension)のまとめ ref: http://qiita.com/shoheiyokoyama/items/16593eb170860acd7344

file2.swift

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        coordinator.animate(alongsideTransition: { [weak self] context in
            self?.textLabel.alpha = 0.3
            self?.imageView.alpha = 0.3
        }, completion: { [weak self] _ in
            self?.textLabel.alpha = 1
            self?.imageView.alpha = 1
        })
}

file3.swift

public enum NCUpdateResult : UInt {

    //最新の情報を表示したい場合
    case newData
    //最新状態から変更がなく、更新する必要がない場合
    case noData
    //アップデートに失敗した際
    case failed
}

file5.swift

@IBAction func tappedButton(_ sender: Any) {
        let url = URL(string: "todaySample://")
        extensionContext?.open(url!, completionHandler: nil)
}

file6.swift

import NotificationCenter

let widgetController = NCWidgetController()
widgetController.setHasContent(flg, forWidgetWithBundleIdentifier: "com.Today.TodayExtension")

NCWidgetTypes.h

@available(iOS 10.0, *)
public enum NCWidgetDisplayMode : Int {


    case compact // Fixed height

    case expanded // Variable height
}

TodayViewController

// expandedで拡大可能に
self.extensionContext?.widgetLargestAvailableDisplayMode = .expanded

// NCWidgetDisplayModeが変更されるたびに呼ばれるので、ここで拡大時の高さを設定する。
func widgetActiveDisplayModeDidChange(_ activeDisplayMode: NCWidgetDisplayMode, withMaximumSize maxSize: CGSize) {
        if case .compact = activeDisplayMode {
            preferredContentSize = maxSize
        } else {
           preferredContentSize.height = 250
        }
}

TodayViewController.swift

func widgetPerformUpdate(completionHandler: (@escaping (NCUpdateResult) -> Void)) {

        fetchTodayData() { data, error in
            if let _ = error { 
                completionHandler(.failed) 
            } else {
                updateUI(data)
                completionHandler(.newData)
            }
        }
}