iOS Interview Questions and Answers

While the view controller lifecycle is about the controller itself, for the most part, significant to how its root see, that UIView instance, shows up and vanishes onto the screen. I will be explicitly discussing the view controller lifecycle, and it’s relating techniques

There are some events of the UI view controller:-

• LoadView

This event creates the view that the controller manages. It’s only known as once the view controller is made programmatically. This makes it a superb place to create your views in code.

• LoadViewIfNeeded

If just in case the reader of current viewController has not been set nevertheless then this methodology can load the view; however bear in mind, this is often solely out there in iOS >=9.0. Thus if you're supporting iOS <9.0 then do not expect it to come back into the image.

• ViewDidLoad

The viewDidLoad event is merely known as once the view is made and loaded into memory. However, the bounds for the view aren't outlined nevertheless. This is often a superb place to initialize the objects that the view controller goes to use.

• ViewWillAppear

This event notifies the view Controller whenever the view seems on the screen. During this step, the read has bounds that are outlined. However, the orientation isn't set.

• ViewWillLayoutSubviews

This is the primary step within the lifecycle wherever the boundaries are finalized. If you're not victimization constraints or Auto Layout, you most likely wish to update the subviews here. This is often solely out there in iOS >=5.0. Thus if you're supporting iOS <5.0 then do not expect it to come back into the image.

• ViewWillLayoutSubviews

This event notifies the view controller that the subviews are got the wind off. It’s a superb place to form any changes to the subviews once they need to be set. This is often only out there in iOS >=5.0. Thus if you're supporting iOS <5.0 then do not expect it to come back into the image.

• ViewDidAppear

The viewDidAppear occasion fires after the view are introduced on the screen. Which makes it an amazing place to get information from a backend administration or database.

• ViewWillDisappear

The ViewWillDisappear occasion fires when the perspective on introduced see controller is going to disappear, reject, spread or hole up behind other viewController. This is a correct place where you can confine your system calls, negate clock or discharge objects which are bound to that viewController.

• ViewDidDisappear

This is the final step of the lifecycle that anybody can address as this occasion fires soon after the perspective on exhibited see controller has been disappeared, rejected, secured or covered up.

SBJson structure is upheld by iOS. It is a JSON parser and generator for Objective-C. SBJson gives adaptable APIs and extra control that makes JSON taking care of simpler.

You can use the UIKit framework to develop application’s UI. This framework provides drawing model, event handling, views, windows and controls, designed for touch screen interfaces.
This framework provides essential infrastructure for constructing and managing iOS apps, such as view and window architecture for managing user interface, event handling infrastructure to respond to user input, and a model to drive run loop and communicate with the system.

Category: You rarely utilize a classification to add strategies to a current class, for example, one characterized in the Cocoa systems. The consolidated procedures are acquired by subclasses and are vague at runtime from the first techniques for the class. You can likewise utilize classifications of your own classes to Distribute the usage of your private classes into independent source files — for example; you could assemble the techniques for an expansive class into a few classes and put every class in an alternate record. Announce private procedures.

Extension - Extensions add new usefulness to a current class, structure, count, or convention type. This incorporates the capacity to broaden types for which you do not approach the original source code (known as retroactive demonstrating). Expansions are like classifications in Objective-C. (Unlike Objective-C types, Swift extensions do not have names.)

It groups together similar rows that differ in content, but have similar layouts in a UITableView. A UITableView allocates sufficient UITableViewCell objects to just display the content that is visible in the table.
If you set reuseIdentifier to non-nil value, then UITableView will attempt to reuse an allocated UITableViewCell using the same reuseIdentifier when you scroll the table view.
If you do not set the reuseIdentifier, the UITableView will allocate new UITableViewCell objects for new items that will scrolls into view.

An App ID is a two-section string want to build up one or a lot of applications from one advancement group. The string comprises of a Team ID, and a pack ID seeks string, with a period (.) isolating the 2 components. The Team ID is provided by Apple and is exclusive to a selected development team, whereas the bundle ID search string is provided by the developer to match either the bundle ID of one app or a collection of bundle IDs for a bunch of apps. As a result of the majority consider the App ID as a string, they suppose it's interchangeable withBundle ID.

It seems this manner as a result of once the App ID is formed within the Member Center, you merely ever use the App ID Prefix that matches the Bundle ID of the applying Bundle. The bundle ID unambiguously defines every App. it's laid out in Xcode. One Xcode project will have multiple Targets and thus output different apps. A typical use case for this can be associate degree app that has each lite/free and pro/full versions or is branded in various ways that.

The application has not been propelled or was running but instead was ended by the framework.

• Inactive

The application is running in the foreground area yet is presently not getting events. It might execute other code, however. An application typically remains in this state just quickly as it changes to an alternate state.

• Active

The application is running in the foreground area and is accepting events. This is the ordinary mode for frontal area applications.

• Background

The application is out of sight and executing code. Most applications enter this state quickly on their approach to being suspended. In any case, an application that demands additional execution time may stay in this state for a timeframe. What's more, an application being launched directly into the background enters this state rather than the idle state. For data about how to execute code while out of sight, see Background Execution.

• Suspended

The application is in the background yet isn't executing code. The framework moves applications to this state naturally and does not inform them before doing as such. While suspended, an application stays in memory yet does not execute any code.

Objective-C doesn't support technique overloading. Thus you have got to use totally different technique names.