Here are some of the most commonly asked iOS interview questions and answers to help you succeed in your next interview.
1. Speaking of iOS, can you highlight the main difference between synchronous and asynchronous tasks?
A synchronous task is one which potentially waits until the completion of a particular task; whereas, an asynchronous task is one which induces completion of the task in the background. 2. In iOS, what do you understand by B trees?
Principally, B-trees are nothing but fundamental search trees. Schematically, B-trees may be imagined as containing nodes and their respective children. Each node contains a sorted array of its own individual elements and a separate array for its children. This is precisely how the B-trees are structured in iOS. 3. Can you define what dynamic dispatch is?
So far as dynamic dispatch is concerned, it is essentially a procedure of selection while implementing a fundamentally polymorphic operation. Usually, the concerned polymorphic function is either a method or a function to be invoked at run time. 4. What do you understand by completion handlers?
Completion handlers, as the name suggests, act as fundamental closures. For instance, they are especially useful in the case of making an API call. Apart from that, they are exceptionally viable in such instances as when you need to upgrade the UI to show the data from the API call. 5. Can you highlight certain easy ways to consolidate the tenet of usability in design?
Simply put, a design process should be viewed holistically and with an open mind. Innovative outreach is key to the development of a successful design. It is important to consider the cognitive orientation of the future user. Apart from that, it is extremely vital to continue tinkering with your app even after it’s been launched in order to come up with better, if any, conclusions.
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6. Can you tell us something about the decorator design pattern in iOS?
In order to supplement behaviors and responsibilities to an object without in the least tampering with the code, it is imperative to consult the decorator design pattern. Chiefly, you can also understand it by considering it as a viable alternative to subclassing. For instance, programming applications such as Objective C and Swift have their own peculiar decorator design patterns in order to avail of them in accordance with situational crises. 7. Since you mentioned Swift, what do you understand by generics and lazy in Swift?
So far as generics are concerned, they are usually helpful in furnishing optimization for your code. As the name suggests, generics are typically not concerned about the specifications of the underlying data types. On the other hand, lazy is an extremely feasible for innovative developers while working with Swift. The typical characteristic of lazy is that the initial value of the properties stored in lazy only when the property is invoked for the first time. 8. What is ‘defer’?
Defer is defined as a keyword which furnishes a block of code to be executed when the execution is about to leave the present scope. 9. How do you pass a variable as a reference?
Technically, you need to treat both as separate variables. One is the value type and the other a reference type. By passing the former, the variable will create a copy of its data. On the other hand, by passing the reference type, it will just point to the original data type located in the memory. This is how you pass a variable as a reference. 10. Explain MVVM?
So far as MVVM is concerned, it is the UIKit independent representation of the View and its corresponding state. As far as the working goes, the View Model induces certain alterations in the model and updates itself with the new Updated Model. The view model is essentially meant to take in your model in order to sort the information to be displayed in your own model.
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