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Swift Interview Questions
Swift is a powerful and intuitive programming language for iOS, iPadOS, macOS, tvOS, and watchOS. Apple Inc. is the company behind it. Writing Swift code is interactive and fun, the syntax is concise yet expressive, and Swift includes modern features developers love. Swift code is safe by design, yet also produces software that runs lightning-fast.
 
It is based on the Objective C runtime library, which enables the execution of C, Objective C, C++, and Swift code in the same program. 
 
Swift has been integrated with Xcode since version 6, 7, 10.x, 11.x, 13.x and is built with the open-source LLVM compiler and can be used for creating both the front end and back end functionalities of applications.

Xcode supports source code for the programming languages: C, C++, Objective-C, Objective-C++, Java, AppleScript, Python, Ruby, ResEdit (Rez), and Swift, with a variety of programming models, including but not limited to Cocoa, Carbon, and Java. Third parties have added support for GNU Pascal, Free Pascal, Ada, C#, Go, Perl, and D. etc,.
Following are the features of Swift :
 
* Type Safety and Type inference language
* Protocol oriented
* Safe by default
* Enforced initializers
* Forced Unwrapping
* Less code, fewer files
* Closures
* Tuples
* Much faster when compared to other languages.
* More impressive structs and enums
* Not required to use semicolons
Swift programming language has speedily become one of the quick-growing languages in memoir. Swift makes us develop software that is incredibly fast, robust and secure.
 
This language is the most useful programming language that is used to develop an application for macOS and iOS(iPad and iPhone).
 
There are some important advantages offered by developing apps for macOS and iOS using swift.
 
Open-source language : The Swift programming language has been created as an open-source and is being open to everyone, this makes it simple for the program to upgrade all the source codes, email lists and bug tracker at regular intervals.

Easy to learn and maintain : Swift programing language is more simple and accurate when compared to C/C++. Apple evolved its programing language to be easy to use and syntaxes are taken from programming languages such as C#, Python, and Ruby. These simple syntax of this programing language make it more meaningful. In swift, all the content of the implementation (.m) and header (.h) files are combined in a single file that is (.swift).

Supported by multiple devices : Swift programming language is not just limited to support Apple devices, it will also support multiple devices of the technology world like Linux and Windows devices.

Supports dynamic libraries : Dynamic libraries are the executable chunks of the code that can be connected to an app. This feature allows the latest swift programing language. In swift, dynamic libraries are directly uploaded to the memory, thereby resulting in deduction down on the initial size of the app and finally increases app performance.

Optional types : An optional in swift is a type that can be held either as a value or not. To declare an optional, we can use a question “?” mark.

Closures : Closures are self-contained blocks of functionality that can be passed around and used in our code.
In Swift, question mark "?" is used in property declaration. It tells the compiler that this property is optional. The property may hold a value or not. It avoids runtime errors when accessing that property by using ?. This is useful in optional chaining and a variant of this example is in conditional clauses.
 
Syntax :
var optionalName : String? = "Chanti"  
if optionalName != nil {  
    print("Your name is \(optionalName!)")  
}
Swift supports several types of operators. One of them is Half Open Range operator. The half open range operator specifies a range between two values a and b (a<b) where b is not included. It is known as half open range operator because it contains its first value only not the final value.
Functions are the set of codes used to perform specific task. In Swift programming language, functions are used to pass local as well global parameter values inside the function's call.
 
In Swift4, functions can be categorized in two types :
 
* User Defined Functions
* Built-in Functions (Library Functions)
Functions and methods can be used interchangeably, but there is a small difference between both of them.  Methods belong to struts, classes, and enums, but functions do not.

Syntax : 
func thisIsAFunction1() {

}

struct Person {
func thisIsAMethod1() {

  }
}
Swift provides a standard set of built-in data types which are used for different purposes :
 
Int : It is used to store the integer value

String :
String literals are used to define the text that contains double quotes in Swift.

Double and Float :
They are used in Swift when we have to define decimal value or number.

Arrays :
Arrays are defined for the collection of list items.

Bool : It is used to store the Boolean value. It uses ‘True’ and ‘False’ conditions

Dictionaries :
A dictionary is used to collect items of a similar type that is connected with a unique key.
Dictionary is similar to the hash tables in other programming languages. It speeds up the entries available in the table. Each entity uses its key in the table, which can be of any Boolean type such as string or number. These keys can be used to retrieve the concurrent value that can be of any value.
Following are some tools used to develop iOS applications :
 
Xcode : It is an iOS development tool that is used for both iOS apps and MAC OS. The graphic interface in Xcode is used to write code for iOS 8 with Apple’s Swift programming language.

Alcatraz : If you want to add Xcode in your application, you can use Alcatraz. It worked as a package manager for Xcode and used to install multiple plug-ins in your IDE. This tool is only available for Xcode 5+ and OSX 13.x+.

Marvel : It will convert sketches into collective prototypes. We can add paper sketches to the app, Adobe Creative Cloud, from Dropbox or we, can draw the sketch directly to the app. After adding the sketch, add tappable hot spots in your image to connect screens together. Now, you can export your web clip on a home page.

Cocoa Controls : It is a list of code used in iOS applications which includes more than 1000 libraries from the open-source community.