🇭🇰 _Hong Kong App Developer; Android, iOS & Firebase lover; Sharing & Writing can strengthen my knowledges!
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AlarmManager is a bridge between application and Android system alarm service. It can send a broadcast to your app (which can be completely terminated by user) at a scheduled time and your app can then perform any task accordingly.

With the help from PendingIntent and Intent, a bundle of information can also be sent together with the system broadcast to your application when alarm goes off.

However, since Android KitKat (API 19) and Android MarshMallow (API 23), Google has added different restrictions on AlarmManager to reduce the battery usage. Alarm no longer goes off exactly at the assigned time by…


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  1. Right-to-left layout support
  2. Vertical orientation (Scroll vertically)
  3. modifiable Fragment collections


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NFC stands for “Near Field Communication”. Two electronic devices can transmit data through NFC when they are distanced fewer than 4 cm apart. NFC can be used for electronic payment. It was invented many years ago but it has just been introduced by Apple to iPhone series since the launch of iPhone7 in 2016. To test an app with NFC feature, a real device must be used instead of an iOS simulator.


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In order to ensure a good quality of app, developers should test their app with a set of simulated location points. Unlike Android, which can use third party app (e.g. MockGPS) to mimic user’s current location, iOS is restricted and developers have to create a GPX file.

The location simulation is very simple and only has 3 steps…


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Sending emails is a common digital marketing technique. However, setting up your own SMTP server and maintaining its security can be a difficult task for many business parties. In addition, you have to make sure to keep your servers up-to-date to keep them secure and take a lot of other steps to prevent your emails from being classified as spam.

Firebase provides a simple to use extension — Trigger Email for handling email delivery. Developers just need to register for an SMTP service provider and create a document with specific fields (e.g. to, subject and text). …


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Let’s get started!

Step-By-Step instruction

Step 1: Enable Proximity Monitoring


Proximity sensor can detect a short distance (~5cm)

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Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store