Quick Answer: Swift Guard Keyword

What is difference between if let and guard in Swift?

guard let will unwrap an optional for you, but if it finds nil inside it expects you to exit the function, loop, or condition you used it in.

However, the major difference between if let and guard let is that your unwrapped optional remains usable after the guard code..

What is #if in Swift?

Swift if (if-then) Statement Here expression is a boolean expression (returns either true or false ). If the expression is evaluated to true , statements inside the code block of if is executed. If the expression is evaluated to false , statements inside the code block of if are skipped from execution.

What is optional in Swift?

An 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.

Is Swift typed?

Swift is strongly typed. Whenever you use a variable or pass something as a function argument, Swift checks that it is of the correct type. You can’t pass a string to a function that expects an integer etc. Swift does this check at compile time (since it’s statically typed).

What is Self in Swift?

In Swift self is a special property of an instance that holds the instance itself. Most of the times self appears in an initializer or method of a class, structure or enumeration. … Or accessing the property from a method brings sufficient context to omit self from self.

What is unwrapping in Swift?

Unwrapping an optional means that you are now casting that type as non-optional. This will generate a new type and assign the value that resided within that optional to the new non-optional type. This way you can perform operations on that variable as it has been guaranteed by the compiler to have a solid value.

What is the guard keyword in Swift?

A guard statement is used to transfer program control out of a scope if one or more conditions aren’t met. A guard statement has the following form: guard condition else { statements.

What is defer keyword in Swift?

The defer keyword is new in Swift 2 and lets you schedule some code to be run at a later date. That later date is when your code exits its current scope, which might be when a function returns or at the end of a loop, for example. If you’ve used other programming languages, defer will seem similar to try/finally .

What keyword is used inside a Guard statement to leave its scope?

Guard statements MUST transfer control away from its enclosing scope, in order to leave the scope it is written in. In this case, it must leave the function, via the “return” keyword.

Do try catch Swift?

The 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 .

What is tuple in Swift?

Tuples in Swift occupy the space between dictionaries and structures: they hold very specific types of data (like a struct) but can be created on the fly (like dictionaries). They are commonly used to return multiple values from a function call.

How do you defer a script?

The defer attribute is a boolean attribute. When present, it specifies that the script is executed when the page has finished parsing. Note: The defer attribute is only for external scripts (should only be used if the src attribute is present).