Then I call it in the view controller to decode the JSON: Which allows a linked up button to move to the next word in the array. Var vocabNumber = 0 (To handle moving from one vocab to another) The struct file I have (vocabHandler) is this: Apologies for the messy code, I’m still learning. I’ve been trying to solve for over a week but to no avail. I’m trying to save a view count for items in an array when the user goes to the next item in the array. We still need the nil-coalescing operator to default to an empty array of String objects if stringArray(forKey:) returns nil.Hey guys I’m having a problem with my first ever app I’ve been building. We can omit the as? operator because the convenience method returns a value of type ?. Var strings: = userDefaults.stringArray(forKey: "myKey") ?
We can simplify the previous example using this convenience method. The stringArray(forKey:) method returns a value of type ?, an optional array of String objects. The UserDefaults class defines one convenience method for reading or getting an array of objects, more specifically an array of String objects. You can read more about this technique in this post.
#USER DEFAULTS SWIFT CODE#
This avoids code duplication and it also results in a cleaner API. If you need to perform this task in several places in your project, I recommend creating an extension for the UserDefaults class to make that task easier. We pass in the array of strings and the key we used to retrieve the array of strings.
#USER DEFAULTS SWIFT UPDATE#
To update the array of strings in the user's defaults database, we need to invoke the set(_:forKey:) method on the shared defaults object. The next step is appending a string to the array of strings. It's as simple as that.īecause we want to append a value to the array of strings, we define strings as a variable instead of a constant. What does that mean? If the key-value pair doesn't exist, we start with an empty array of strings. Notice that we use the nil-coalescing operator to default to an empty array of String objects. Var strings: = userDefaults.object(forKey: "myKey") as? We start by retrieving the array from the user's defaults database. Updating an array or appending a value to an array in the user's defaults database shouldn't be difficult with what you have learned so far. Updating or Appending a Value to an Array In User Defaults A runtime exception is thrown if the key that is passed to object(forKey:) doesn't exist or if the result can't be cast to an array of String objects. I strongly discourage you from using the as! operator to forced cast the result of object(forKey:) to an array of strings. The strings constant is of type ?, an optional. Let strings = userDefaults.object(forKey: "myKey") as? This means we need to cast the result of object(forKey:) to an array of String objects using the as? operator. Remember that object(forKey:) returns an object of type Any?. We invoke the object(forKey:) method on the shared defaults object, passing in the key of the value we are interested in, myKey in this example. Let strings = userDefaults.object(forKey: "myKey")
#USER DEFAULTS SWIFT HOW TO#
Let me show you how to retrieve that array of strings. In the first example, we stored an array of String objects in the user's defaults database. The object(forKey:) method returns an object of type Any?, an optional. The UserDefaults class doesn't define a convenience method for easily accessing an array of values stored in the user's defaults database and that is why we use the object(forKey:) method. Reading or getting an array from the user's defaults database is straightforward. Reading or Getting an Array From User Defaults What happens if we pass the array to the set(_:forKey:) method? The result is a runtime exception because URL isn't supported by the defaults system.
We create a URL object and store it in an array. This approach doesn't work if we try to store an array of an unsupported type, for example, an array of URL objects. We pass the array of strings as the first argument and a key as the second argument. We then create an array of strings and store the array in the user's defaults database by invoking the set(_:forKey:) method of the UserDefaults database. We access the shared defaults object through the standard class property of the UserDefaults class. You can only store arrays of strings, numbers, Date objects, and Data objects in the user's defaults database. You probably know that you can store strings, numbers, Date objects, and Data objects in the user's defaults database. Writing or Setting an Array To User Defaults I promise you that it isn't rocket science. In this post, I show you how to store an array in the defaults database. You can take advantage of the API on iOS, tvOS, macOS, iPadOS, and watchOS.
Storing data in the defaults database is simple thanks to the easy-to-use API of the UserDefaults class.
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