- #Save dictionary array in user defaults swift how to
- #Save dictionary array in user defaults swift archive
UserDefaults caches the information to avoid having to open the user’s defaults database each time you need a default value. Storing large amount of data into UserDefaults could affect performance of your app significantly as the whole UserDefaults plist file is loaded into memory when your app launches. A better way to do this is to save the image file (eg: avatar.png) into the Library folder of app, then store the path to the image (eg: "AppFolder/Library/avatar.png") into UserDefaults, and show the image using UIImage(contentsOfFile: savedPath).
User can then tap the recent trips when they select station.Īvoid storing large amount of data in a single UserDefaults key such as 50 rows of user's favorite songs.Īnd also avoid storing image data (conversion of UIImage to NSData) into UserDefaults, as UserDefaults are not meant to store large amount of data. In my public transport app Komuter, the last 5 trips are stored in UserDefaults (Array of custom objects encoded into NSData). You can also store non-sensitive data such as high score for a game, recently played song etc. You can use UserDefaults for storing user settings (eg: settings page in your app with UISwitch, Segmented Control or simple Textfield) Apps store these preferences by assigning values to a set of parameters in a user’s defaults database. In the documentation, Apple mentioned few example use cases :įor example, you can allow users to specify their preferred units of measurement or media playback speed. If we want to store custom object into UserDefaults, we can use Codable and PropertyListEncoder to turn the custom object into NSData. plist format to save data, we can only store data with type of NSString, NSNumber, NSData, NSArray, NSDictionary or NSData. plist file, Xcode will show a property list format to us :Īs UserDefaults uses. You will see two folder, 'Caches' and 'Preferences', the UserDefaults plist file is stored inside the 'Preferences' folder. userDomainMask, true)īuild and run the app in Simulator, then open Finder and press command + shift + G, paste in the library path and click 'Go' to navigate to the Library folder. Let library_path = NSSearchPathForDirectoriesInDomains(.libraryDirectory. We can take a peek into the Library folder like this : ("", forKey: "homepage") The UserDefaults plist is saved in the Library folder inside the app folder ( Read more on app folder structure here). When you store data in UserDefaults, the data format is similar to ist as well. There is usually an ist file created for you when you start new iOS project : plist file before, plist is short for property list. what is a property list? 🤔 What does "A default object must be a property list" means?
#Save dictionary array in user defaults swift archive
If you want to store any other type of object, you should typically archive it to create an instance of NSData.
What type of data can we store in UserDefaults?Ī default object must be a property list-that is, an instance of (or for collections, a combination of instances of) NSData, NSString, NSNumber, NSDate, NSArray, or NSDictionary.
#Save dictionary array in user defaults swift how to
How to decide which approach to use for saving data? 🤔Īs per Apple Documentation, UserDefaults isĪn interface to the user’s defaults database, where you store key-value pairs persistently across launches of your app. UserDefaults, Keychain and Core Data are some of the most popular ways to persist data (so that the data is still there the next time user launch your app after quitting). There are many ways to store data locally in iOS app.
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