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IOS Development Interview questions 2021
Q1) Is the multitasking function is supported by iOS?
Ans: Multitasking function is supported by the iOS 4 & the other high-level series. This series supports the app to run in the background once they are launched and they keep running unless they are terminated. This is the highly extraordinary future showcased by the iOS application platform.
Q2) Among the different JSON frameworks which one does support iOS?
Ans: iOS supports the SBJson framework. It is a well advanced and highly flexible framework that supports the flexible functioning of APIs & and some other extra added features that make the JSON handling a lot easier. SBJson is a highly advanced concept of the iOS software platform.
Q3) What do you understand by the term App Bundle?
Ans: A bundle can simply be defined as a directory that groups up all the related resources together at one place within the file system. For example, if you build an iOS app, Xcode packages then it can be called a bundle. Inside an iOS app bundle, it contains all the application files which can be executable. App Bundle also supports the resource different files which include localized content, image files, and app icons. These elements help in delivering the best application performance to the iOS software.
Q4) What do you understand by Cocoa/Cocoa touch?
Ans: Both OS X & iOS are having different application development environments. Cocoa and Cocoa touch can simply be interpreted as the application development environment for the same OS X and iOS.
Having the main objective of developing applications for different platforms, Cocoa is extensively been designed to develop applications that run on OS X platform and whereas Cocoa touch is being used for developing applications that run on the iOS platform.
Q5) What do you understand by the term NSFetchRequest?
Ans: Fetch requests are extensively used for fetching predefined objects which match the exact requirement in-relation to individual values, criteria and much more. The main use of this NSFetcherRequest is to fetch from the core data.
Q6) What do you understand by the word subscripts?
Ans: Subscripts can simply be interpreted as a set of shortcuts that are used for accessing the member elements of a list or any sequence. Different classes, structures, and enumerations can be defined as the set of subscripts.
Q7) What do you understand by the term NS Persistent Container?
Ans: NSPersistentContainer can be interpreted as a property that has been developed in order to create and return a container that has loaded the store for the application to it. Actually, this is a critical process to get done and it may fail to deliver legitimate error conditions.
Q8) What do you understand by the term NS Fetched Results Controller?
Ans: NSFetchedResultsCounter is a most liked part by the developers as it makes their lives by simply abstracting away much of the coding part which is used to synchronize a table view that has a data source backed by core data. Though it is a controller it’s not a view controller and has no user interface.
Q9) What do you know about the concept of Nil Coalescing & Ternary Operator?
Ans: NilCoalescing & Ternary Operator can simply be interpreted as an easy return and unwrapped optional value. In the case where we are not having any value to assign, we can set zero or any default choice of our need.
Q10) Explain the benefits of the guard?
Ans: Guard is an advanced aspect of iOS which has is being used extensively. Going deep into the aspects of the guard things will be quite fascinating. There are two major benefits of a guard.
The first benefit of using a guard is that it helps in avoiding the Pyramid of Doom. This is very much helpful as it can be seen in the case where the nested statements tend to move further ahead towards the right.
The other benefit of using the guard is that making use of the break or return functions creates an opportunity for an early exit from the loop.
Q11) Explain the terms KVC-KVO
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Ans: KVC-The term KVC relates to Key-Value Coding. It is a technique in which the properties of the object can be accessed within the run time by using the concept of strings and it helps to know the different property names within the time of development.
KVO-The term KVO stands for Key-Value Observing. The main function of this is to observe the changes that occur to property value. The other specification of KVO is that an object it helps in notifying the user whenever a specific property changes its value.
Q12) Explain the layer objects and where do they present?
Ans: Layer objects are one of the simple application elements that are delivered to perform various applications. In the general layer, objects can be interpreted as the data objects that represent visual content. These layer objects will help the views to render their content. The best feature of this is that custom layer objects can be created and get them added to the interface to perform complex animations and other such related highly sophisticated visual effects.
Q13) In the case of iOS application getting crashed what are the things you are going to do?
Ans: It is quite obvious in seeing the applications getting crashed and the performance goes down. In such cases the sequential steps which are done to find the best solution to the mentioned problem are
* At first, get the exact steps to reproduce the crashed application.
* Then the next thing to be done is to find out the iOS version of that particular device.
* Then check if the version is the latest or not?
* And at the end try to get device logs if possible.
[Related Article: iPhone Tutorial]
Q14) Depict the reasons why is it better to use higher-order functions?
Ans: Higher-order functions can simply be interpreted as the functions that take up the value of another function as a parameter, or a return function. These higher-order functions are collective types and the filter is expressed as a basic higher-order function.
Q15) Explain the word protocol and its function.
Ans: A protocol helps in defying a list of applications that are required for a class to perform if it adopts that particular protocol.
A protocol functioning will be similar to that of an interface in Java programming. The protocol can be implemented by any class & all the other classes can send messages to that class based on protocol implements by simply not knowing the exact type of the class.
Q16) Differentiate between the concepts of viewDidLoad and viewDidAppear.
Ans: When the view has loaded the function which is called is viewDidLoad. This can be done either from a Xib file, or any programmatically created in lead View.
ViewDidAppear can be called anytime whenever the view is presented on the device. Depending on the case of your data you can decide which function to be used.
Q17) State the difference between the concepts of not-running, and suspended states.
Ans: The major difference between the not-running and the suspended states are
Not running: The term not running refers to the case where the app has not been launched yet and is or it was previously running but is now closed by the system.
Suspended: The term suspended relates to the case where the app is running in the background but it is not executing any code. Though the app is suspended it still remains in the in-memory. The system can also purge the suspended apps the case where the system is running out of storage.
Q18) Explain the concepts of inactive and active states.
Ans: Inactive: This is an indication that the app is running in the foreground but is currently not receiving events. An app will be seen in this state only for a brief period of time and then it transmits to another state.
Active: The app is running in the foreground and is receiving events. This means that the app is active and is running the coding action.
Q19) Differentiate the concepts of copy and retain?
Ans: Retaining in the sense relates to the aspect in which the total count increases by one. This states that the instance of the object will be kept in memory unless it retains count totally drops to the value of null or zero.
Whereas, the term Copy indicates that the object will be cloned with duplicate values.
Q20) Explain what is defer?
Ans: The term defers can simply be interpreted as a keyword that provides a block of code that will be executed in the case when execution is leaving the current scope.
Q21) Explain the procedure of passing a variable as a reference
Ans: At first, it is a well-known aspect that variables are of two types which are mainly referenced and value types.
The major variations between these both types of variables are that by passing value types the variable will then generate a duplicate of the data within and whereas the reference type variable will simply point the actual data in the memory.
Q22) Explain lazy in Swift
Ans: The lay properties are a lot of help for iOS developers. In the context of lazy, the value of the lay at the initial value is calculated only when it been called for the first time
Q23) What is Defer and explain?
Ans: Defer is a keyword, it can simply be interpreted and offers a series of code that can be executed in the block of codes at the time of execution that leaves the current scope.
Q24) Explain About The Major Swift main advantage
Ans: The major benefits of Swift are well explained here below.
* Optional Types, which make applications crash-resistant
* Much faster compared to other languages.
* Built-in error handling
* Type-safe language
* It is best known to support pattern matching.
Q25) What are the benefits of Relam?
Ans: Relam is considered to be one among the best iOS platform. The benefiting aspects of this concept are
* An open-source database framework.
* Implemented from scratch.
* Zero-copy object store.
Q26) Explain the concept of SQLite limits.
Ans: SQLite Limits is one of the most advanced development concepts of the iOS application platform. The in-depth functioning aspects of SQLite Limits include
* At first defining the relations between the tables is quite necessary.
* Then work on defining the schema of all the tables.
* Then all the queries must be manually written in order to fetch the data.
* We need to query results and then map those to models.
* Queries are very fast.
Q27) Explain the concept of JSON/PLIST limits?
Ans: JSON/PLIST is the highly advanced application software that is effectively employed in the iOS application platform.
Some of the major concepts of JSON/PLIST Limits include
* At first the objects are created and serialized them to disk..
* It’s great and very limited use cases.
* It’s quite obvious that no one uses the complex queries to filter your results.
* It’s very slow.
* Serialize or Deserialization is the concept that is most extensively used iOS aspects.
* It’s not thread-safe.
Q28) What is the Memento Pattern?
Ans: In Memento Pattern is effectively employed within the iOS application platform framework. It plays a vital role in saving your stuff somewhere.
And then, the externalized state can never be taken back else it becomes the violating encapsulation. All the private personal information will be transferred safely.
One of Apple’s specialized implementations of the Memento pattern is Archiving other hand iOS uses the Memento pattern as part of State Restoration.
Q29) What is the Observer Pattern?
Ans: The observer pattern is one of the internal functioning aspects of the iOS application platform. In the Observer pattern, one object notifies other objects of any state changes.
Q30) What is the Facade Design Pattern:
Ans: The Facade design pattern furnishes the best known for providing a single interface to a complex subsystem. With the aid of Facade Design Pattern, In spite of using a user to a group of classes with their APIs, you only compose one simple unified API.