What is nil in Swift?

Hear this out loudPauseIn 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.

How check object is nil or not in Swift?

Hear this out loudPauseIn 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.

What is optional unwrapping in Swift?

Hear this out loudPauseForced Unwrapping optionals in Swift Force Unwrapping an optional either returns the value if it exists or triggers a runtime error when the optional is nil . But before we dive into force unwrapping, lets first go over the possibilities of unwrapping an optional without force.

What are optionals Swift?

Hear this out loudPauseAn optional in Swift is basically a constant or variable that can hold a value OR no value. The value can or cannot be nil. It is denoted by appending a “?” after the type declaration. This is a big impact on the language Swift itself because what that means is that anything non-optional types can never be nil.

What is the meaning of in Swift?

Hear this out loudPausemoving or capable of moving with great speed or velocity; fleet; rapid: a swift ship. coming, happening, or performed quickly or without delay: a swift decision. quick or prompt to act or respond: swift to jump to conclusions. Slang. quick to perceive or understand; smart; clever: You can’t cheat him, he’s too swift.

What is @autoclosure in Swift?

Hear this out loudPauseSwift’s @autoclosure attribute enables you to define an argument that automatically gets wrapped in a closure. It’s primarily used to defer execution of a (potentially expensive) expression to when it’s actually needed, rather than doing it directly when the argument is passed.

Do try catch Swift?

Hear this out loudPauseThe try/catch syntax was added in Swift 2.0 to make exception handling clearer and safer. It’s made up of three parts: do starts a block of code that might fail, catch is where execution gets transferred if any errors occur, and any function calls that might fail need to be called using try .

Is Swift similar to Python?

Hear this out loudPauseSwift is more similar to languages such as Ruby and Python than is Objective-C. For example, it’s not necessary to end statements with a semicolon in Swift, just like in Python. If you cut your programming teeth on Ruby and Python, Swift should appeal to you.

What is type-safe in Swift?

Hear this out loudPauseSwift is a type-safe language. A type safe language encourages you to be clear about the types of values your code can work with. If part of your code requires a String , you can’t pass it an Int by mistake. If you don’t specify the type of value you need, Swift uses type inference to work out the appropriate type.

Is Swift type-safe?

Hear this out loudPauseSwift is a type-safe language. A type safe language encourages you to be clear about the types of values your code can work with. If part of your code requires a String , you can’t pass it an Int by mistake.

What is $0 and $1 in Swift?

Hear this out loudPause$0 and $1 are Closure’s first and second shorthand arguments (a.k.a. Shorthand Argument Names or SAN for short). The shorthand argument names are automatically provided by Swift. The first argument can be referenced by $0 , the second argument can be referenced by $1 , the third one by $2 , and so on.

How does the nil coalescing operator work in Swift?

Because isEmpty returns true when there’s a whitespace. Nil coalescing operator checks if the optional is not nil, in case it is not nil it then checks its property, in this case isEmpty. Because this optional can be nil you provide a default value which will be used when your optional is nil.

Which is the equivalent of a nil literal in Swift?

Optional.none is equivalent to the nil literal. Optional.some (Wrapped) stores a wrapped value. For example: You must unwrap the value of an Optional instance before you can use it in many contexts. Because Swift provides several ways to safely unwrap optional values, you can choose the one that helps you write clear, concise code.

How to check if string is nil or empty in Swift?

It is used similarly to the if statement, but it allows for early return and just makes for much cleaner code in general. To use guard when checking to make sure that a string is neither nil nor empty, you can do the following: This unwraps the optional string and checks that it isn’t empty all at once.

How to use optionals in a program in Swift?

It unwraps an optional a and returns it if it contains a value, or returns a default value b if a is nil. When you run the program, the output will be: In the above program, variable someValue is defined optional and contains nil value. The nil coalescing operator fails to unwrap the optional therefore returns defaultValue.