将deviceToken由Data类型转换为String，其实方法很简单，swift当中的具体做法就是：
在 application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) 方法中，实现以下代码：
let nsdataStr = NSData(data: deviceToken)
let datastr = nsdataStr.description.replacingOccurrences(of: "<", with: "").replacingOccurrences(of: ">", with: "").replacingOccurrences(of: " ", with: "")
print("deviceToken:(datastr)")
