Overview
- Optional Binding. To conditionally bind the wrapped value of an Optional instance to a new variable, use one of the optional binding control structures, including if let, guard let, and ...
- Optional Chaining. ...
- Using the Nil-Coalescing Operator. ...
- Unconditional Unwrapping. ...
How do you use optional binding?
You use optional binding to check if the optional contains a value or not. If it does contain a value, unwrap it and put it into a temporary constant or variable. There is no better way to explain optional binding than using an example.
How do you bind an optional variable to a variable?
To conditionally bind the wrapped value of an Optional instance to a new variable, use one of the optional binding control structures, including if let, guard let, and switch. To safely access the properties and methods of a wrapped instance, use the postfix optional chaining operator (postfix ?).
What is optional chaining and optional binding in Swift?
Keeping this in consideration, what is optional chaining and optional binding in Swift? The process of querying, calling properties, subscripts and methods on an optional that may be 'nil' is defined as optional chaining.
What are the optional binding for the if statement in Swift?
An optional binding for the if statement is as follows −. Let's take a simple example to understand the usage of optional binding −. var myString:String? myString = "Hello, Swift 4!". if let yourString = myString { print("Your string has - (yourString)") } else { print("Your string does not have a value") }.
What is optional binding in IOS?
Optional Binding is used to safely unwrap the optional value. Step Two: If the optional variable contains a value it will be assigned to our temporary variable. Step Three: When the program executes it will execute the first branch and unwrap our optional safely.
What is optional binding and optional chaining?
Optional binding stores the value that you're binding in a variable. 2. Optional chaining doesn't allows an entire block of logic to happen the same way every time. 2. Optional binding allows an entire block of logic to happen the same way every time.
What is optional in Swift?
An Optional is a type on its own, actually one of Swift 4's new super-powered enums. It has two possible values, None and Some(T), where T is an associated value of the correct data type available in Swift 4.
How can we use optional binding to determine if the variable String is not nil?
How To Use Optional BindingFirst, we create a constant named optionalUsername of type String?, and assign it a string value. ... Then, we use optional binding to assign the value of optionalUsername to the constant username if it's not nil. ... Finally, when optionalUsername is not nil, we print out the value of username.
What is the use of optional chaining?
You can use optional chaining when attempting to call a method which may not exist. This can be helpful, for example, when using an API in which a method might be unavailable, either due to the age of the implementation or because of a feature which isn't available on the user's device.
What is optional chaining in Javascript?
The optional chaining '?. ' is an error-proof way to access nested object properties, even if an intermediate property doesn't exist.
What is optional value?
An optional value either contains a value or contains nil to indicate that the value is missing.
What is optional unwrapping in Swift?
Unwrapping in Swift is essentially verifying if the Optional value is nil or not, and then it performs a task only if it's not nil. You can perform unwrapping in the following ways: Using an if else block. Using Forced unwrapping. Using Optional binding.
How is optional implemented in Swift?
Implementing Integer optionals in Swift So optionals can be implemented through an enum (with associated value). Calling it “Optional” when there is no value is not ideal, but matches the internal implementation.
Why do we need optional in Swift?
An optional value allows us to write clean code with at the same time taking care of possible nil values. If you're new to Swift you might need to get used to the syntax of adding a question mark to properties. Once you get used to them you can actually start benefiting from them with, for example, extensions.
What is optional in Swift and nil in Swift and Objective-C?
In Swift, nil means the absence of a value. Sending a message to nil results in a fatal error. An optional encapsulates this concept. An optional either has a value or it doesn't. Optionals add safety to the language.
Is optional an enum?
Optional is actually an enum, defined in relation to a generic type Wrapped. It has two cases: . none to represent the absence of a value, and . some to represent the presence of a value, which is stored as its associated value of type Wrapped.
Scenario One
Let us imagine we find a box in front of our doorstep. We did not expect to receive anything today but are curious to see what’s inside. It can either be a package that came early or possibly just an empty box left on the door. It was pretty windy yesterday, so it could just sweep on our doorstep.
Scenario Two
We are asked questions during science class about how many stars are in the universe, but we have no idea because we can’t count every star! So we tell the professor that we have no idea how many stars are in the galaxy so we make a wild guess of 33 and after a final guess of 66 stars.
Optional Binding
So we have been talking about optional binding, so let us cover how this works and why it is essential. Optional binding is common practice when unwrapping nil values safely. So let us go step by step on how the binding process works.
Conclusion
Life is too short not to take risks. Understand nothing will come with a few days’ work and dedicate yourself to the process. Success is made over time, not overnight. Happy coding!
What does an optional value mean in Swift?
An Optional is a type on its own, actually one of Swift 4’s new super-powered enums. It has two possible values, None and Some (T), where T is an associated value of the correct data type available in Swift 4. Here’s an optional Integer declaration −.
Can you unwrap an optional variable?
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 Binding
To conditionally bind the wrapped value of an Optional instance to a new variable, use one of the optional binding control structures, including if let, guard let, and switch.
Optional Chaining
To safely access the properties and methods of a wrapped instance, use the postfix optional chaining operator (postfix ? ). The following example uses optional chaining to access the hasSuffix (_:) method on a String? instance.
Using the Nil-Coalescing Operator
Use the nil-coalescing operator ( ??) to supply a default value in case the Optional instance is nil. Here a default path is supplied for an image that is missing from imagePaths.
Unconditional Unwrapping
When you’re certain that an instance of Optional contains a value, you can unconditionally unwrap the value by using the forced unwrap operator (postfix ! ). For example, the result of the failable Int initializer is unconditionally unwrapped in the example below.
Coalescing Nil Values
Performs a nil-coalescing operation, returning the wrapped value of an Optional instance or a default value.
Comparing Optional Values
Returns a Boolean value indicating whether two optional instances are equal.
Inspecting an Optional
Hashes the essential components of this value by feeding them into the given hasher.
