Difference between App Bundle and File Directory

Ans : Although bundles and packages are sometimes referred to interchangeably, they actually represent very distinct concepts:

1.
A package is any directory that the Finder presents to the user as if it were a single file.
A bundle is a directory with a standardized hierarchical structure that holds executable code and the resources used by that code.

2.
The Finder considers a directory to be a package if any of the following conditions are true:
.The directory has a known filename extension: .app, .bundle, .framework, .plugin, .kext, and so on.
.The directory has an extension that some other application claims represents a package type; see Document Packages.

Difference between array, set and dictionary

Ans : 

Array :
Arrays are effectively ordered lists and are used to store lists of information in cases where order is important.
Cost of adding item in array is greater than set and dictionary if item is not appending first.

For example, posts in a social network app being displayed in a tableView may be stored in an array.

Set : 
Sets are different in the sense that order does not matter and these will be used in cases where order does not matter. Sets are especially useful when you need to ensure that an item only appears once in the set.

Dictionary : 
Dictionaries are used to store key, value pairs and are used when you want to easily find a value using a key, just like in a dictionary.


For example, you could store a list of items and links to more information about these items in a dictionary.

What is NSPredicate?

Ans : Using NSPredicate, we can filter records before fetching from Coredata or collections. It work in place of where clause in sql.

NSPredicate on Core Data :

When we want data from coredata of only who's name is Manan Shah. So using predicate we can filter as following :

var strName = "Manan Shah"
request.predicate = NSPredicate(format: "name = %@", strName)

NSPredicate on Collections : 

let manan = Person(firstName: "Manan", lastName: "Shah", age: 28)
let sagar = Person(firstName: "Sagar", lastName: "Shah", age: 26)

let people = [manan, sagar] as NSArray

let thirtiesPredicate = NSPredicate(format: "age >= 27")

people.filtered(using: thirtiesPredicate)
Result : manan object will be return.

What is safe area?

Ans: The Safe Area Layout Guide helps avoid underlapping System UI elements when positioning content and controls.

The Safe Area is the area in between System UI elements which are Status Bar, Navigation Bar and Tool Bar or Tab Bar. So when you add a Status bar to your app, the Safe Area shrink. When you add a Navigation Bar to your app, the Safe Area shrinks again.

On the iPhone X, the Safe Area provides additional inset from the top and bottom screen edges in portrait even when no bar is shown. In landscape, the Safe Area is inset from the sides of the screens and the home indicator.

The layout guide (Safe area) representing the portion of your view that is unobscured by bars and other content. In iOS 11+, Apple is deprecating the top and bottom layout guides and replacing them with a single safe area layout guide.

In iPhone X portrait, safe area insets from top(notch) and bottom(home) side, and
in landscape, left(notch/ home bar) and right side(home bar/notch) and also bottom side.

We can enable using of safe area layout guide property of view controller from class inspector.

Difference between SOAP and REST

Ans : 

1. Requests sent via REST tend to be much lighter than SOAP. Because of this, applications don't require much bandwidth to use REST web services over SOAP.

2. REST is good when working with web services open to the public, but if security is required, then the SOAP API is better to use. 

3. SOAP permits XML data format only while REST permits Plain text, HTML, XML, JSON etc.

i.e 

Suppose we want to retrieve today's weather report from a server which is providing weather information, your RESTful URL will look something like http://weatherdata.org/data/weather/uk/london (Not real link just example url), which is very similar to HTTP request like http://weatherdata.org/data/weather?q=uk,London.

On the other hand, in order to get the same data using SOAP, you need to create an XML message with header and body and send it http://www.webservicex.net/globalweather.asmx?op=GetWeather. 

In short, RESTfull web services are much simpler, flexible and expressive than SOAP web services in Java.