IOS interview questions for experienced/IOS Interview Questions and Answers for Freshers & Experienced

How do I start a career in iOS development with no experience?

To start a career in iOS development with no experience, you can follow this roadmap:

1. Learn iOS development
2. Practice what you learned by making apps
3. Attend conferences to learn what other developers are talking about
4. To have a portfolio of work, you can start putting your projects on GitHub
5. Developing apps for small organizations at a low cost or for free

Posted Date:- 2021-10-15 12:05:42

Which coding knowledge should I know for iOS development?

To become an iOS developer, you must be proficient in Swift. It is an intuitive coding language created by Apple for building apps for iOS, Mac, Apple TV, and Apple Watch. Swift programming language is open-source and easy to use.

Posted Date:- 2021-10-15 12:04:07

How long does it take to learn iOS development?

If you are a beginner, it would take you at least six months to learn iOS development from scratch. If you can study for several hours per day, you will be able to learn much faster. In a few months, you will likely know the foundations of iOS and be able to build a simple iOS app.

Posted Date:- 2021-10-15 12:03:15

How many are there APIs for battery-efficient location tracking ?

There are 3 apis.
Significant location changes — the location is delivered approximately every 500 metres (usually up to 1 km)
Region monitoring — track enter/exit events from circular regions with a radius equal to 100m or more. Region monitoring is the most precise API after GPS.
Visit events — monitor place Visit events which are enters/exits from a place (home/office).

Posted Date:- 2021-10-15 12:02:32

What are the educational requirements to become an iOS developer?

To become an iOS developer, you will need to have a Bachelor’s degree in computer science, software engineering, or any other related field. In addition to this, some senior positions may require a few years of experience in software development experience or iOS development.

Posted Date:- 2021-10-15 12:01:36

Are iOS developers in demand?

Due to the ever-increasing popularity and demand for Apple devices, there is a high demand for iOS developers. There is a shortage of iOS developers in the market at all levels – entry, mid, and senior-level. Experienced as well as entry-level professionals are entering this field as it offers endless job opportunities offering excellent remuneration.

Posted Date:- 2021-10-15 12:00:51

What are the major roles and responsibilities of an iOS developer?

The major roles and responsibilities of an iOS developer are:

1. Designing and creating advanced applications for the iOS platform
2. Ensuring the quality of the application
3. Collaborating with cross-functional teams to design and ship new features
4. Test codes for robustness, and reliability
5. Fixing application bugs and improving application performance
6. Implementing application updates
7. Continuously discover, evaluate, and implement new technologies for maximum efficiency

Posted Date:- 2021-10-15 12:00:06

What skills are needed for iOS developer jobs?

The top skills required to become an iOS developer are:

1. Swift Programming Language
2. iOS Platform
3. C-based Libraries
4. APIs and Cloud Messaging
5. Spatial Reasoning
6. Design Guidelines
7. UI and UX design
8. Core Data
9. Grand Central Dispatch
10. Networking

Posted Date:- 2021-10-15 11:59:01

What job roles and profiles are available in iOS development?

Some of the job titles in the field of iOS development are:

1. Engineer
2. Software Developer
3. Software Engineer
4. Architect
5. Principal Architect
6. iOS Developer
7. Senior iOS Developer
8. Lead Developer
9. Principal Developer
10.Principal Engineer

Posted Date:- 2021-10-15 11:57:29

What is JSON/PLIST limits ?

We create your objects and then serialized them to disk..

It’s great and very limited use cases.

We can’t obviously use complex queries to filter your results.

It’s very slow.

Each time we need something, we need to either serialize or deserialize it.

it’s not thread-safe.

Posted Date:- 2021-10-15 11:56:02

Is an iOS developer a good career in 2021?

An iOS developer is an in-demand career that offers lucrative salaries and job security. iOS developers often perform creatively challenging work and contribute to a wide variety of projects. There are huge job opportunities in the iOS field that provide good pay packages and better career growth.

Posted Date:- 2021-10-15 11:55:02

Name the APIs for battery-efficient location tracking?

Following are three types of APIs:

* Significant location changes: the location is delivered approximately every 500 meters (usually up to 1 km)
* Region monitoring: track enter/exit events from circular regions with a radius equal to 100m or more. * Region monitoring is the most precise API after GPS.
* Visit events: monitor place Visit events which are enters/exits from a place (home/office).

Posted Date:- 2021-10-15 11:54:12

Mention the Realm benefits?

Following are the Realm benefits:

<> An open-source database framework.
<> Zero copy object-store.
<> Implemented from scratch.
<> Fast.

Posted Date:- 2021-10-15 11:53:19

Why is the use of a design pattern in Linux?

Design patterns are used to solve common problems in software design. These design patterns use different templates to help you write code that is easy to understand. Look at some common Cocoa design patterns:

< Creational: Singleton.
< Behavioral: Observer, and, Memento
< Structural: Decorator, Adapter, Facade

Posted Date:- 2021-10-15 11:52:25

What is Memento Pattern?

In Memento Pattern saves your stuff somewhere. Later on, this externalized state can be restored without violating encapsulation; that is, private data remains private. One of Apple’s specialized implementations of the Memento pattern is Archiving other hand iOS uses the Memento pattern as part of State Restoration.

Posted Date:- 2021-10-15 11:51:12

Outline the class hierarchy for a UIButton until NSObject.

UIButton inherits from UIControl, UIControl inherits from UIView, UIView inherits from UIResponder, UIResponder inherits from the root class NSObject.

Posted Date:- 2021-10-15 11:50:13

What are layer objects?

Layer objects are data objects which represent visual content and are used by views to render their content. Custom layer objects can also be added to the interface to implement complex animations and other types of sophisticated visual effects.

Posted Date:- 2021-10-15 11:49:25

Differentiate between the ‘assign’ and ‘retain’ keywords.

Retain -specifies that retain should be invoked on the object upon assignment. It takes ownership of an object.
Assign – specifies that the setter uses simple assignment. It is used on attributes of scalar type like float, int.

Posted Date:- 2021-10-15 11:48:57

What is an autorelease pool?

Every time – autorelease is sent to an object, it is added to the inner-most autorelease pool. When the pool is drained, it simply sends – releases to all the objects in the pool.
Autorelease pools are a convenience that allows you to defer sending -release until “later”. That “later” can happen in several places, but the most common in Cocoa GUI apps is at the end of the current run loop cycle.

Posted Date:- 2021-10-15 11:48:22

What is Decorator Design Pattern?

The Decorator pattern dynamically adds behaviors and responsibilities to an object without modifying its code. It’s an alternative to subclassing where you modify a class’s behavior by wrapping it with another object.
In Objective-C there are two very common implementations of this pattern: Category and Delegation. In Swift there are also two very common implementations of this pattern: Extensions and Delegation.

Posted Date:- 2021-10-15 11:47:48

What is the purpose of reuseIdentifier? What is the benefit of setting it into a non-nil value?

The reuseIdentifier is used to group together the similar rows in a UITableView, i.e., the rows that differ only in their content, otherwise having similar layouts. A UITableView will normally allocate just enough UITableViewCell objects to display the content visible in the table.

If reuseIdentifier is set to a non-nil value, then the UITableView will first attempt to reuse an already allocated UITableViewCell with the same reuseIdentifier when the table view is scrolled. If reuseIdentifier has not been set, then the UITableView will be forced to allocate new UITableViewCell objects for each new item that scrolls into view, potentially leading to laggy animations.

Posted Date:- 2021-10-15 11:47:00

What is a plist?

Property list or plist refers to a list that organizes data into named values and lists of values using several object types. These types provide us the means to produce data that is meaningfully structured, transportable, storable, and accessible, but still as efficient as possible. Property lists are frequently used by applications running on both Mac OS X and iOS. The property-list programming interfaces for Cocoa and Core Foundation allow us to convert hierarchically structured combinations of these basic types of objects to and from standard XML. We can save the XML data to the disk and later use it to reconstruct the original objects.

The user defaults system, which we programmatically access through the NSUserDefaults class, uses property lists to store objects representing user preferences. This limitation would seem to exclude many kinds of objects, such as NSColor and NSFont objects, from the user defaults system. However, if objects conform to the NSCoding protocol, they can be archived to NSData objects, which are property-list-compatible objects.

Posted Date:- 2021-10-15 11:46:24

Does Objective-C contain private methods?

No, there is nothing called a private method in Object-C programming. If a method is defined in .m only, then it becomes protected; if it is defined in .h, it is public.

If we really want a private method, then we need to add a local category/unnamed category/class extension in the class and add the method in the category and define it in class.m.

Posted Date:- 2021-10-15 11:45:56

How can you prevent the iOS 8 app's streaming video media from being captured by QuickTime Player on Yosemite during screen recording?

HTTP live streams that have their media encrypted will not be recorded by QuickTime Player on Yosemite while screen recording. These will blackout in the recording. HTTP live streaming: It sends live and on‐demand audio and video to iPhone, iPad, Mac, Apple TV, and PC with HTTP live streaming (HLS) technology from Apple. Using the same protocol that powers the web, HLS lets us deploy the content using ordinary web servers and content delivery networks. HLS is designed for reliability and dynamically adapts to network conditions by optimizing playback for the available speed of wired and wireless connections.

Posted Date:- 2021-10-15 11:45:30

What is the difference between atomic- and non-atomic properties? Which is the default for synthesized properties? When would you use one over the other?

Properties specified as atomic are guaranteed to always return a fully initialized object. This also happens to be the default state for synthesized properties. While it is a good practice to specify atomic properties to remove the potential for confusion, if we leave it off, the properties will still be atomic. This guarantee of atomic properties comes at the cost of performance. However, if we have a property for which we know that retrieving an uninitialized value is not a risk (e.g., if all access to the property is already synchronized via other means), then set it to non-atomic can boost the performance.

Posted Date:- 2021-10-15 11:44:49

What is SpriteKit and what is SceneKit?

SpriteKit is a framework for easy development of animated 2D objects.

SceneKit is a framework inherited from OS X that assists with 3D graphics rendering.

SpriteKit, SceneKit, and Metal are expected to power a new generation of mobile games that redefine what iOS devices’ powerful GPUs can offer.

Posted Date:- 2021-10-15 11:43:52

When is an app said to be in active state?

An app is said to be in active state when it is running in the foreground and is receiving events.

Posted Date:- 2021-10-15 11:43:23

When is the category used?

It is used to add a set of related methods and to add additional methods in the Cocoa framework.

Posted Date:- 2021-10-15 11:42:57

What is Method Swizzling?

The process of changing the implementation of an existing domain, Method Swizzling, enables you to write that code that can be executed before or after the original method.

Posted Date:- 2021-10-15 11:42:00

When would you say that an app is not in a running state?

An app is said to be in ‘not running’ state in the following cases:
– When it is not launched.
– When it gets terminated by the system during running.

Posted Date:- 2021-10-15 11:41:38

Which API would you use to write test scripts to exercise the application’s UI elements?

UI Automation API is used to automate test procedures. JavaScript test scripts that are written to the UI Automation API simulate user interaction with the application and return log information to the host computer.

Posted Date:- 2021-10-15 11:41:11

Which framework is used to construct the application’s user interface?

UIKIT framework. It renders drawing models, windows, event handling, and views.

Posted Date:- 2021-10-15 11:40:48

What is Facade Design Pattern?

The Facade design pattern provides a single interface to a complex subsystem. Instead of exposing the user to a set of classes and their APIs, you only expose one simple unified API.

Posted Date:- 2021-10-15 11:39:33

Explain QOS?

QoS stands for the quality of service. It is a class that organizes the work that NSOperation, NSOperationQueue, NSThread artifacts, dispatch queues, and threads do (POSIX threads). By assigning a QoS, you’re telling the system how important it is, and the system prioritizes and schedules it accordingly.

Posted Date:- 2021-10-15 11:37:56

Explain the lazy property in Swift?

A lazy stored property is one that does not determine its initial value until it is used for the first time. The lazy modifier is written before the declaration of a lazy stored property.

Posted Date:- 2021-10-15 11:37:32

What is meant by deadlock?

A deadlock is a situation that occurs when at least two threads are locked on a different resource, and both are waiting for the other resource to finish its job. And no one is able to unlock the resource it is guarding.

Posted Date:- 2021-10-15 11:37:15

Why is design pattern very important ?

Design patterns are reusable solutions to common problems in software design. They’re templates designed to help you write code that’s easy to understand and reuse. Most common Cocoa design patterns:

* Creational: Singleton.
* Structural: Decorator, Adapter, Facade.
* Behavioral: Observer, and, Memento

Posted Date:- 2021-10-15 11:36:58

What is ABI?

ABIs are important when it comes to applications that use external libraries. If a program is built to use a particular library and that library is later updated, you don’t want to have to re-compile that application (and from the end user's standpoint, you may not have the source). If the updated library uses the same ABI, then your program will not need to change. ABI stability will come with Swift 5.0

Posted Date:- 2021-10-15 11:36:10

Why is the design pattern very important?

Design patterns are important in software design because design patterns are reusable solutions to many common problems. They’re models for writing code that’s simple to comprehend and reuse. The most popular design trends in Cocoa are as follows:

Creational: Singleton.
Structural: Decorator, Adapter, Facade.
Behavioral: Observer, and, Memento

Posted Date:- 2021-10-15 11:35:51

How to Prioritize Usability in Design?

To prioritize usability, the design process has broken down into 4 steps:

* Consider the user’s perspective when designing the user experience.

* Users, not demographics, are what you should focus on.

* Consider all of the scenarios in which an app might be useful when promoting it.

* Even after the app has been released, continue to improve its functionality.

Posted Date:- 2021-10-15 11:35:26

Differentiate between a frame and a bound?

A UIView’s bounds are a rectangle with a size (width, height) and position (x,y) relative to its own coordinate system (0,0).

A UIView’s frame is a rectangle with a scale (width, height) and position (x,y) relative to the superview it is located within.

Posted Date:- 2021-10-15 11:34:37

What is SpriteKit and what is SceneKit?

SpriteKit is a platform for creating animated 2D objects quickly and easily.

SceneKit is a platform for 3D graphics rendering that was inherited from OS X.

SpriteKit, SceneKit, and Metal are expected to boost a new generation of mobile games that push the boundaries of what the powerful GPUs in iOS devices can do.

Posted Date:- 2021-10-15 11:34:20

What are the different ways to specify the layout of elements in UIView?

Here are a few common ways to specify the layout of elements in UIView:

* Using InterfaceBuilder, we can add a XIB file to our project, layout elements within it, and then load XIB in our application code (either automatically, based on naming conventions, or manually). Also, using InterfaceBuilder, we can create a storyboard for our application.
* We can write our own code to use NSLayoutConstraints and have elements in a view arranged by Auto Layout.
* We can create CGRects describing the exact coordinates for each element and pass them to UIView’s (id)initWithFrame:(CGRect)frame method.

Posted Date:- 2021-10-15 11:34:03

What is Dynamic Dispatch?

At runtime, Dynamic Dispatch determines which implementation of a polymorphic procedure, such as a method or a function, to call. This means that when we want to call our methods, such as object methods, we must use this syntax. Swift, on the other hand, does not use dynamic dispatch by default.

Posted Date:- 2021-10-15 11:33:17

What is GCD?

The GCD stands for Grand Central Dispatch. It is a low-level API that allows you to manage multiple concurrent operations. It will assist you in increasing the responsiveness of your app by deferring computationally intensive tasks to the context. It’s a simpler concurrency model than locks and threads to deal with.

Posted Date:- 2021-10-15 11:32:59

Explain the different types of iOS Application States.

You will experience a few app states while using the application. There are five states in the ios application as follows.

* Not Running

The application is in the Not running state, if the app is not launched yet or if the application is not visible on the screen or also there is the possibility that the application is terminated by the user or by OS.

* Inactive

An inactive state occurs when the application is not receiving events but the app is running in the background. An app transitions to a different state. when the user locks the screen or the system prompts the user to respond to some event such as a phone call or SMS message is the only time it stays inactive.

* Active

In an ios application, Active State is the main executive state. In this state, the app is running in the foreground and the UI is accessible.

* Background

Before being suspended most of all apps enter this state. If an app requests extra execution time then that will remain in this state for some more time. Also, an application will be launched directly into the background enters this background state instead of the inactive state

* Suspended

In a suspended state the application does not execute any code. The system purges suspended apps without any notice to make more space for the foreground app when a low-memory condition occurs.

Posted Date:- 2021-10-15 11:32:43

What is the difference between KVC and KVO?

KVC (Key-Value Coding) is a method for accessing an object’s properties using strings at runtime rather than needing to know the property names statically at development time.
KVO (Key-Value Observing) allows a controller or class to monitor changes in a property value. In KVO, an object may request to be informed of any adjustments to a particular property, and the observer is automatically notified if that property’s value changes.

Posted Date:- 2021-10-15 11:31:47

What is an NSError in Swift?

The NSError class is a Cocoa class. The knowledge about an error condition is encapsulated in an extendable, object-oriented manner by an NSError object. It includes a predefined error domain, a domain-specific error code, and a user details dictionary with application-specific data.

Posted Date:- 2021-10-15 11:31:31

What is Swift and what is Objective-C?

Swift is a modern programming language created by Apple for iOS, OS X, watchOS, and tvOS apps that combines the best of C and Objective-C, but without the C compatibility issues. Swift follows secure programming patterns while also incorporating modern features to make programming simpler, more versatile, and enjoyable. Swift is welcoming to novice programmers and feels familiar with Objective-C developers.

The primary programming language for writing applications for OS X and iOS is Objective-C. It’s an object-oriented programming language with a dynamic runtime that’s a superset of the C programming language. Objective-C takes C’s syntax, primitive types, and flow control statements and adds class and process definition syntax.

Posted Date:- 2021-10-15 11:31:14

What are UI Elements in iOS?

The visual elements that we can see in our applications are known as UI elements. Some of these components, such as buttons and text fields, respond to user interactions, while others, such as images and labels, provide information.

Posted Date:- 2021-10-15 11:31:00

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