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lazy variables are variables will be computed until accessing. In other words, lazy variables won't have the real value until get called/used. As lazy variables can be re-assigned, so it can't be used on constants which normally defined by let.

One example of using lazy variables:

Scenarios of use

One of the good use scenarios is we can use the lazy feature on View initialization setup. For example, if the view have multiple states, such as empty list or populated list, they can be lazily loaded when in different situation, so the compiler won’t have to compute both of the two views (empty and populated) at one time.

What about Objective-C

Objective-C doesn’t natively support the lazy, but some simple workout can be easily implemented.


Originally published at on December 31, 2020.



Once you have finished the SwiftUI code, it is always a good idea to preview it before implement any function code. Luckily, such feature is natively supported by SwiftUI — PreviewProvider:

Example of showing previews:

The preview:



This article demonstrates how to connect iMessage service to your Android phone/pad so that you can contact your iPhone friends freely from now on. To finish the article will take 5 mins.


  • A mac laptop or server
  • Android Phone
  • iPhone (optional for testing)

Features of AirMessage:

  • Safe: all the…



What is Swift Package?

According to Apple’s doc:

For developers, Swift Package has the native support from Apple, which is recommended way of using 3rd libraries.

How to use

Go to FileSwift PackageAdd Package Dependency: