App Extension: Notifiation Content

NotificationViewController.swift

import UIKit
import UserNotifications
import UserNotificationsUI

// 可考虑在 info.plist 里限定初始高与屏幕高的比例，比如 0.3，但不建议使用1。体验一下加载图片的效果就知道为什么了
class NotificationViewController: UIViewController, UNNotificationContentExtension {

    //@IBOutlet var label: UILabel?
    @IBOutlet var imageView: UIImageView! // 建议在storyboard限定图片最大高度和最大宽度，避免图片被截断
    //@IBOutlet var containerView: UIView!

   // 最终显示尺寸的秘密：
   // 1. 对imageView的约束，会给出最终显示尺寸的信息； 
   // 2. 或在 viewDidLoad() 指定 preferredContentSize

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any required interface initialization here.
        view.backgroundColor = .white // Xcode自动创建的默认为蓝色
    }

    func didReceive(_ notification: UNNotification) {
        let c = notification.request.content
        //label?.text = c.body
        // if UTTypeConformsTo(kUTTypeJPEG as CFString, kUTTypeImage as CFString) {
        //   print(true)
        // }
        for a in c.attachments {
            print(a)
            if a.url.startAccessingSecurityScopedResource() {
                let data = try! Data.init(contentsOf: a.url)
                // 若不用 async，就显示不出来。
                // Debug 时此处打断点，能显示图片
                DispatchQueue.main.async {
                    let i = UIImage(data: data)
                    self.imageView.image = i
                    //imageView.setNeedsDisplay()
                }

                a.url.stopAccessingSecurityScopedResource()
            }
        }
    }

    func didReceive(_ response: UNNotificationResponse, completionHandler completion: @escaping (UNNotificationContentExtensionResponseOption) -> Void) {
        print(response)
        completion(.dismissAndForwardAction)
    }

}