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Answer» The several methods for unwrapping an optional in Swift are as follows: - Forced unwrapping: It consists in adding a ! after an Optional value, to automatically unwrap it, without having to check whether it is nil or not. Example - let v:STRING = b!
Optional chaining: The technique of querying and calling properties, methods, and subscripts on an optional that is currently nil is known as optional chaining. The PROPERTY, method, or subscript call SUCCEEDS if the optional includes a value; if the optional is nil, the property, method, or subscript call returns nil. Multiple inquiries can be chained together, and if any link in the chain is nil, the entire chain will fail gracefully. Example -
let v = b?.count- Nil coalescing operator: If there is a value inside an optional, the nil coalescing operator unwraps it and returns it. If no value is provided – for example, if the optional is nil – a default value is used instead. The result will not be optional in either case: it will be either the value from within the optional or the default value used as a backup. Example -
let v = b ?? ""- Optional pattern: An optional pattern matches items wrapped in an Optional<Wrapped> enumeration's some(Wrapped) case. Optional patterns appear in the same places as enumeration case patterns and consist of an identifier pattern followed by a question mark. An example is given below:
if case let v? = b { print(v)}- Guard statement: When certain requirements are not met, the guard statement in Swift is used to shift PROGRAM control out of scope. With one key exception, the guard statement is comparable to the if statement. When a given condition is met, the if statement is executed. The guard statement, on the other hand, is executed when a given condition is not met. Example is given below:
guard let v = b else { return}- Optional binding: Optional binding is used to determine whether or not an optional has a value. If it does have a value, unwrap it and save it in a temporary variable or constant. Example is given below:
if let v = b { print("b has been unwrapped with success and is = \(v)")}- Implicitly unwrapped variable declaration: Because a variable may start life as nil, but will always have a value before you need to use it, implicitly unwrapped optionals exist. It's helpful not to have to write if let all the time because you know they'll have value by the time you need them. Example:
var v = b!
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