How expensive NSTimeZone is

Question

How expensive it is to create [NS]TimeZone? Meaning it is cheaper to have a single

static let utc = TimeZone(abbreviation: "UTC")

or have

TimeZone(abbreviation: "UTC")

all over the place (as I see in one MR I;m currently reviewing)

Answer 1

Instantiation of a timezone will not take any noticeable time compared to everything else your app does. You will not see any app performance difference between the 2 in normal use.

The best thing is to just make sure your code is clean. Don't spray TimeZone(abbreviation: "UTC") through your code, wrap it in a helper method which does what ever date formatting you are doing, and call it from where you need it so you can localize all the date functions in 1 spot.

Answer 2

Creating a TimeZone object using TimeZone(abbreviation: "UTC") or using a static let like static let utc = TimeZone(abbreviation: "UTC") has different performance implications.

Creating a TimeZone object using TimeZone(abbreviation: "UTC") every time you need it will incur a small overhead each time it's created because it involves creating a new instance of the TimeZone class, parsing the abbreviation string, and performing some initialization tasks.

On the other hand, using a static let like static let utc = TimeZone(abbreviation: "UTC") creates a single instance of the TimeZone object and initializes it once. This instance is then reused wherever utc is accessed in your code, which can be more efficient in terms of memory and performance. It's essentially a form of caching.

So, if you have multiple places in your code where you need to work with the UTC time zone, using a static let like utc can be more efficient as it avoids creating a new instance of TimeZone every time you need it. It's a good practice in cases where you have a frequently used and unchanging object.

However, this performance difference is usually minimal and might not be noticeable unless you are creating a very large number of TimeZone objects frequently. In most cases, code readability and maintainability should be a higher priority. If you have a good reason to create a new TimeZone object each time, then you should do what makes sense for your specific use case.