Do you put a semicolon after every statement in Swift?
Unlike many other languages, Swift doesn’t require you to write a semicolon (;) after each statement in your code, although you can do so if you wish. However, semicolons are required if you want to write multiple separate statements on a single line: Integers are whole numbers with no fractional component, such as 42 and -23.
What is a colon in a sentence?
Colons (:) introduce clauses or phrases that serve to describe, amplify, or restate what precedes them. Often they are used to introduce a quote or a list that satisfies the previous statement.
What are the control transfer statements in Swift?
Swift has five control transfer statements: a break statement, a continue statement, a fallthrough statement, a return statement, and a throw statement. A break statement ends program execution of a loop, an if statement, or a switch statement.
What are the different branch statements in Swift?
Swift has three branch statements: an if statement, a guard statement, and a switch statement. Control flow in an if statement or a switch statement can be changed by a break statement and is discussed in Break Statement below.
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What is Colon used for in Swift?
Colon(:) is basically used to specify the type of any variable in swift. It is used in many other places as well like in dictionaries to separate key and value pair. Show activity on this post. Semicolon in swift can be used to terminate a statement but it is not required.
What does _: mean in Swift documentation?
The underscore indicates that there is no external parameter name for the function. Apple's Swift Documentation talks about this concept in terms of when you're writing your own functions.
What does .type mean in Swift?
In Swift, there are two kinds of types: named types and compound types. A named type is a type that can be given a particular name when it's defined. Named types include classes, structures, enumerations, and protocols. For example, instances of a user-defined class named MyClass have the type MyClass .
What are optionals 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.
Are semicolons required in Swift?
Semicolons. Unlike many other languages, Swift doesn't require you to write a semicolon ( ; ) after each statement in your code, although you can do so if you wish. However, semicolons are required if you want to write multiple separate statements on a single line: let cat = "🐱"; print(cat)
What is a tuple in Swift?
In Swift, a tuple is a group of different values. And, each value inside a tuple can be of different data types. Suppose we need to store information about the name and price of a product, we can create a tuple with a value to store name (string) and another value to store price (float)
What are closures in Swift?
In Swift, a closure is a special type of function without the function name. For example, { print("Hello World") } Here, we have created a closure that prints Hello World . Before you learn about closures, make sure to know about Swift Functions.
What does .self mean in Swift?
In Swift, the self keyword refers to the object itself. It is used inside the class/structure to modify the properties of the object. You can assign initial values to properties in the init() method via self.
What are value types in Swift?
Types in Swift fall into one of two categories: first, “value types”, where each instance keeps a unique copy of its data, usually defined as a struct, enum, or tuple. The second, “reference types”, where instances share a single copy of the data, and the type is usually defined as a class.
What is a lazy VAR in Swift?
A lazy var is a property whose initial value is not calculated until the first time it's called. It's part of a family of properties in which we have constant properties, computed properties, and mutable properties.
What is unwrap 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.
Why optionals are useful 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 escaping in Swift?
In Swift, a closure marked with @escaping means the closure can outlive the scope of the block of code it is passed into. In a sense, @escaping tells the closure to “stay up even after the surrounding function is gone”.
How do you write a documentation comment in Swift?
Type /// or /** */ to begin a documentation comment and then use DocC's special dialect of Markdown to write the content. This dialect supports many keywords like - Parameters: for describing function arguments or - Returns: for describing return values.
What is in keyword in Swift?
The start of the closure's body is introduced by the in keyword. This keyword indicates that the definition of the closure's parameters and return type has finished, and the body of the closure is about to begin.
How do you mark a comment in Swift?
The // MARK: and // MARK: - syntax in Swift functions identically to the #pragma mark and #pragma mark - syntax in Objective-C. When using this syntax (plus // TODO: and // FIXME: ), you can get some extra information to show up in the quick jump bar. It exists mostly to help with quick navigation within the file.
How does Swift interpolate?
Swift uses string interpolation to include the name of a constant or variable as a placeholder in a longer string, and to prompt Swift to replace it with the current value of that constant or variable. Wrap the name in parentheses and escape it with a backslash before the opening parenthesis:
When to use double or float in Swift?
Swift always chooses Double (rather than Float) when inferring the type of floating-point numbers. If you combine integer and floating-point literals in an expression, a type of Double will be inferred from the context: let anotherPi = 3 + 0.14159. // anotherPi is also inferred to be of type Double.
What is a tuple in Swift?
Tuples enable you to create and pass around groupings of values. You can use a tuple to return multiple values from a function as a single compound value. Swift also introduces optional types, which handle the absence of a value. Optionals say either “there is a value, and it equals x ” or “there isn’t a value at all”.
What is Swift programming?
Swift is a new programming language for iOS, macOS, watchOS, and tvOS app development. Nonetheless, many parts of Swift will be familiar from your experience of developing in C and Objective-C. Swift provides its own versions of all fundamental C and Objective-C types, including Int for integers, Double and Float for floating-point values, ...
Why is Swift type safe?
If part of your code requires a String, you can’t pass it an Int by mistake. Because Swift is type safe, it performs type checks when compiling your code and flags any mismatched types as errors.
What is control flow in Swift?
Control flow statements are used to control the flow of execution in a program. There are several types of control flow statements in Swift, including loop statements, branch statements, and control transfer statements. Loop statements allow a block of code to be executed repeatedly, branch statements allow a certain block of code to be executed only when certain conditions are met, and control transfer statements provide a way to alter the order in which code is executed. In addition, Swift provides a do statement to introduce scope, and catch and handle errors, and a defer statement for running cleanup actions just before the current scope exits.
What are the three types of statements in Swift?
Statements. In Swift, there are three kinds of statements: simple statements, compiler control statements, and control flow statements. Simple statements are the most common and consist of either an expression or a declaration. Compiler control statements allow the program to change aspects of the compiler’s behavior and include a conditional ...
What happens if a while statement is false?
If false, the program is finished executing the while statement. The program executes the statements, and execution returns to step 1. Because the value of the condition is evaluated before the statements are executed, the statements in a while statement can be executed zero or more times.
How many control transfer statements are there in Swift?
Swift has five control transfer statements: a break statement, a continue statement, a fallthrough statement, a return statement, and a throw statement.
When switching over a nonfrozen enumeration value, do you need to include a default case?
When switching over a nonfrozen enumeration value, you always need to include a default case, even if every case of the enumeration already has a corresponding switch case. You can apply the @unknown attribute to the default case, which indicates that the default case should match only enumeration cases that are added in the future. Swift produces a warning if the default case matches any enumeration case that’s known at compiler time. This future warning informs you that the library author added a new case to the enumeration that doesn’t have a corresponding switch case.
How to change control flow in a loop?
Control flow in a loop statement can be changed by a break statement and a continue statement and is discussed in Break Statement and Continue Statement below.
How many branch statements does Swift have?
The values of the conditions specified in a branch statement control how the program branches and, therefore, what block of code is executed. Swift has three branch statements: an if statement, a guard statement, and a switch statement. Control flow in an if statement or a switch statement can be changed by a break statement ...
What is a colon in writing?
Colons (:) introduce clauses or phrases that serve to describe, amplify, or restate what precedes them. Often they are used to introduce a quote or a list that satisfies the previous statement. For example, this summary could be written as "Colons can introduce many things: descriptors, quotes, lists, and more.".
What Is a Colon?
We all know the colon, right? It's a punctuation mark that looks like two dots stacked, like a period with another period hovering above it :
Why do we use colons in prose?
In the running prose that we encounter in books, magazines, articles, and the like, colons are mostly used to introduce a clause or a phrase that explains, illustrates, amplifies, or restates what precedes them. (Reminder: clauses and phrases are both groups of words within a sentence; the basic difference between them is ...
What is an appositive colon?
A colon can also introduce something that acts as an appositive. (Reminder: An appositive is a noun or noun phrase that refers to the same thing as another noun or noun phrase in the same sentence, and is usually right next to that other noun or noun phrase, like in "my neighbor the doctor.". The two nouns/noun phrases—in this case "my neighbor" ...
What is the clause following the colon?
The clause following the colon is in apposition to "this" (which is a pronoun referring to "the crux of it all," if we're going to get technical about it).
Is it hard to find colons in stock photography?
Colons are also hard to find in stock photography, so just go with it .
Is a colon capitalized?
Note that what follow s the colon is not capitalized, but it could be. As a clause—it has its own subject and verb and could in fact function alone as its own sentence, albeit a sentence of the question variety—it certainly looks like something that can start with a capital letter, but whether it does or not is simply a matter of style.
Why is syntax useful in a language?
The language offers useful syntax to improve the readability using argument labels, or to access a tuple or structure component.
Why does Swift warn about unused values?
Because the invocation result of greet ("Alexandra") is not used , the Swift compiler warns about the unused value.
What is underscore in code?
Another common usage of the underscore is to iterate a code block a particular number of times, and ignore the iteration value.
What is a tuple in math?
Tuples are simple data structures that are used to couple related values. They are especially useful when returning multiple values from a function.
What is enumeration in data?
Enumeration is a powerful data structure, especially in combination with associated values. However extracting data from such complex structure has some overhead, especially to access the associated values.
Why is Swift so efficient?
Such practice is efficient, because writing meaningful code has a big impact on understanding: and as result on productivity.
Why is _ used instead of a variable in the loop for _ in 1.exponent?
Since the sequence value on each iteration is insignificant , _ is used instead of a variable in the loop for _ in 1...exponent.
