When you work as a developer everything seems challenging at the beginning whether it is the UI, Logic, Functionality, or Storing the precious data that our user is going to use in day to day life. I want to explain you, why Persisting data is so important in iOS?, and the simplest way for storing the small bits of data using User-default.
What is Data Persistence?
Understanding the meaning of persistence is important as an app developer. The importance of the storing data in most of the modern applications is a challenge, and when achieved then, it provides a better and interactive user experience. Suppose, you were using an app to fill a form, then suddenly you had an incoming call and since calls are the unavoidable interrupts for phones, your app will go to the background and you have to receive the call. When you returned back, you see that you had lost all the data that you put inside the form. This is the problem that we need to solve using data persistence.
Persistence is 'the continuance of an effect after its cause is removed'. In the context of storing data in a computer system or mobiles phones, this means that the data must survive after the quitting of our application.
Why Do We Need to Store Data Locally?
Well, as I stated earlier, interrupts like call or another thing may hamper your important tasks in between on any app. Now, it would be really annoying when your work gets lost and all data is gone so, saving them locally on the device’s memory is very important.
Talking about IOS, there is a life cycle of the app from launching to terminating, and between these, a user performs his/her task. When you press the home button, the apps go in the background i.e. the app you were working on is no longer visible. When your app gets terminated then you lose data in normal apps that you made until you use the data persistence mechanism on IOS for storing data locally on the users’ device.
The life cycle of the IOS app is shown below.
The problem occurs when the app terminates and our data is not stored locally. The terminating of the app can occur in the following scene:
- The operating system is trying to reclaim the resources because the user is trying to use various apps and the memory space just runs out.
- If the user force quit the app for any reasons or by mistake.
- Installing updates can really end up terminating your app.
- If the operating system is updated.
This is one of the ways to persist the data locally. On IOS, The ways we can persist data locally are:
- UserDefaults:-for small bits of data
- Coadables:- saving items inside the documents.
- Coredata:- SQL lite backend database basically we create a relational database.
UserDefaults is one of the easiest ways to locally persist our data. It is an interface to the users’ default database where we store the data in the form of key-value pair across the launches of our app.
The UserDefaults class written by Apple provides us a programmatic interface for interacting with the defaults system. The defaults system allows an app to customize its behavior to match a user’s preferences. For example, you can allow users to specify their preferred units of measurement or media playback speed. Apps store these preferences by assigning values to a set of parameters in a user’s defaults database. The parameters are referred to as default because they’re commonly used to determine an app’s default state at startup or the way it acts by default.