设计推送系统

问题

如何设计 iOS 端的推送系统？

答案

架构

客户端设计

class PushManager {
    // Token 管理
    func didRegisterToken(_ token: Data) {
        let tokenString = token.map { String(format: "%02.2hhx", $0) }.joined()
        // 上报服务端，关联 userId
        API.registerPushToken(token: tokenString, platform: "ios")
    }

    // 消息路由
    func handleNotification(userInfo: [AnyHashable: Any]) {
        guard let type = userInfo["type"] as? String else { return }
        switch type {
        case "chat":
            Router.shared.navigate(to: "myapp://chat?id=\(userInfo["chatId"] ?? "")")
        case "order":
            Router.shared.navigate(to: "myapp://order?id=\(userInfo["orderId"] ?? "")")
        default:
            break
        }
    }
}

// Notification Service Extension - 富文本推送
class NotificationService: UNNotificationServiceExtension {
    override func didReceive(_ request: UNNotificationRequest,
                             withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        guard let content = request.content.mutableCopy() as? UNMutableNotificationContent,
              let imageURL = content.userInfo["image"] as? String,
              let url = URL(string: imageURL) else { return }

        // 下载图片附件
        URLSession.shared.downloadTask(with: url) { localURL, _, _ in
            if let localURL,
               let attachment = try? UNNotificationAttachment(identifier: "image", url: localURL) {
                content.attachments = [attachment]
            }
            contentHandler(content)
        }.resume()
    }
}

---

常见面试问题

Q1: 推送到达率低怎么优化？

答案：APNs 不保证 100% 到达。可以补充长连接通道（WebSocket），App 前台时走长连接，后台走 APNs。同时维护推送回执，排查未达消息。

相关链接

• Apple - APNs