Clear an optional variable in Swift

swift unwrap optional string
swift deallocate object
swift deinitialized
swift unwrap optional array
swift optional parameters
optional chaining in swift medium
optional binding swift
swift deinit super

If I declare an empty image:

var myImage: UIImage?

and then give it a value:

myImage = UIImage(named: "drawing.png")

how can I later remove that value, returning it to its original empty state?

var myImage: UIImage?

Is basically short hand for making a UIImage point to nil automatically.

So to reset it back to the original value say:

myImage = nil

swift How to remove optional String Character, Actually when you define any variable as a optional then you need to unwrap that optional value. To fix this problem either you have to declare  Actually when you define any variable as a optional then you need to unwrap that optional value. To fix this problem either you have to declare variable as non option or put !(exclamation) mark behind the variable to unwrap the option value.

Set its value back to nil like this

myImage = nil

Optional, Because Swift provides several ways to safely unwrap optional values, you can choose the one that helps you write clear, concise code. The following examples​  Hello, Swift 4! Automatic Unwrapping. You can declare optional variables using exclamation mark instead of a question mark. Such optional variables will unwrap automatically and you do not need to use any further exclamation mark at the end of the variable to get the assigned value. Let's take a simple example −

Optional is an enum type in Swift; it has two cases:

enum Optional<T> : NilLiteralConvertible {
    case None
    case Some(T)
    ...
}

By assigning an image to your Optional<UIImage>, you have implicitly specified .Some(image). To clear it, you can use .None. But since Optional also conforms to NilLiteralConvertible, you can use the simpler and clearer nil.

The Complete Guide to Optionals in Swift – Hacking with Swift, An empty optional integer isn't equal to 0, -1, 16777216, or any other values by accident, Swift makes us unwrap the optionals: the process of  In Swift, you can also use nil-coalescing operator to check whether a optional contains a value or not. It is defined as (a ?? b). It unwraps an optional a and returns it if it contains a value, or returns a default value b if a is nil. Example 7: Optional handling using nil-coalescing operator

Declare it as AnyHashable, if there's a need to change the data type of the reference:

var x: AnyHashable
myImage = UIImage(named: "drawing.png")

Optionals, That function doesn't accept any parameters, and it returns a string: "Hate". variable a String? , or just remove the type annotation entirely and let Swift use type  Once we know the optional must contain a value, we unwrap it by placing an exclamation mark (!) to the end of the optional’s name. In Swift this is known as forced unwrapping . You use the ! operator to unwrap an optional and reveal the underlying value.

Optionals In Swift: The Ultimate Guide – LearnAppMaking, You use variables to store information while your Swift code runs; functions execute clearly defined tasks in your code. Let's look at a situation  You can provide a type annotation when you declare a variable, to be clear about the kind of values the variable can store. Here is the syntax − var variableName:<data type> = <optional initial value> The following example shows how to declare a variable in Swift 4 using Annotation.

How to Handle Optionals in Swift - Better Programming, Simply put, an Optional is a way to use nil values in Swift. nil is nothing, and is different from zero ( 0 ) or an empty string ( "" ). This can be  It allows to check the optional and extract its value into a constant or variable as part of a single action. It’s useful when we need to use the unwrapped value many times in the if body. This will be read as “If the optionalInt has a value, extract that value into the constantInt and use it inside of the if body, otherwise print that it

Optional Chaining, Optional chaining in Swift is similar to messaging nil in Objective-C, but in a way defines a variable property called rooms , which is initialized with an empty  Swift also provides powerful versions of the three primary collection types, Array, Set, and Dictionary, as described in Collection Types. Like C, Swift uses variables to store and refer to values by an identifying name. Swift also makes extensive use of variables whose values can’t be changed.

Comments
  • @SapphireBrick. Sure. But looking at the timestamps, this one was the first.