![]() This will happen in the init method of the FSDefaultsObserver class. It’s purpose will be to observe changes to the properties of our own user defaults class that inherits from FSUserDefaults that will call the appropriate set method of UserDefaults with the new value. In addition to a base FSUserDefaults class that we will inherit from (similarly to how it was done in Objective-C), an observer class is needed. ![]() However, KVO can be used to achieve the same effect. That means we can’t provide method implementations at run-time that effectively set and get values from UserDefaults when a property is accessed. In Swift, properties do not have setters and getters generated for them, and the dynamic keyword is used for Key-Value Observing. (For a more detailed look at this, see the old post on NSUserDefaults.) I also tried putting the code inside SceneDelegate.swift but it doesnt work there either. My intent is to create the preferences that the user sets on the app. UserDefault doesnt work, when I change the color of the app, then I close it and reopen it I dont see the changes. ![]() This allows us to dynamically provide the implementation methods for the setter and getter of dynamic properties using the -(BOOL)resolveInstanceMethod: method of NSObject. read a UserDefault value when the app starts. In Objective-C, when you declare a property the compiler generates a setter and getter method along with a backing instance variable. Having now primarily switched over to using Swift for iOS projects, I wanted to take a look at how to go about improving UserDefaults in the same way.Īt first it didn’t look like it was possible to achieve the same simplified API I ended up with for NSUserDefaults because Objective-C properties and Swift properties are fundamentally different. This greatly simplified the string-based API of NSUserDefaults to make it much more convenient and safe to use. A little while ago I wrote a post about improving NSUserDefaults in Objective-C using the Objective-C runtime.
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