Top iOS interview Questions And Answers Collection

1.What are sensors in iPhone?
Answer: 

The proximity sensor immediately turns off the display when the iPhone is lifted to ear.

​With this sensor the power is saved and accidental dialling is prevented.

The display is automatically brightens the iPhone by the ambient light sensor when the sunlight or bright rooms and dims in darker places.
​
2.What is the Advantage of using programmatic UIView?
Answer:
Programmatically constructing UIView's can be verbose and tedious, 

but it can allow for greater control and also easier separation and sharing of code. They can also be more easily unit tested.

​Read:
Where to use atomic in Objective C ?
iOS Interview Questions And Answers Part 7

3. What are all  the newly added frameworks to iOS 8.0?
Answer:-

1.Swift                          2.HealthKit
3.HomeKit                   4.CloudKit
5.SpriteKit                   6.SceneKit
7.Metal                         8.Touch ID API
9.PhotoKit                   10.Camera API

Read:
Best Tutorials- Properties in objective C
Top 5 Simple iOS Interview Questions And Answers

4.What are the (.h) and (.m) files?
Answer:

 .h (header files) contain class, type, function, and constant declarations. So no actual code. Header files are there to let (for instance) xcode know what methods and properties are declared in that specific class.

.m (Class  implementation file) is contains all the implementation details of all the functions declared in .h. It also contains declaration and implementation of private functions that outside classes cannot use, or should not care about.

Read:
What is the difference between IBOutlet and IBAction in iOS ?
Some important points About View Controller.

5.How to synthesize CGFloat in objective C?
Answer:

In general, you no longer need to manually write @synthesize anymore.

In your example, if you write
@property (assign, nonatomic) CGFloat someFloat;

The compiler will automatically synthesize it for you, which would be equivalent to you writing:
@synthesize someFloat = _someFloat;

Hence, you would be able to access the property through self.someFloat or access the ivar within the implementation file by using _someFloat.

If, however, you manually synthesize it like
@synthesize someFloat;

Read:
What are the differences between Cocoa and Cocoa Touch?
Some important notes about View in iPhone.

6. What are the location services?
Answer:

 Applications such as Maps, camera and compass are allowed to use the information from cellular, Wi-Fi and Global Positioning System networks for determining the approximate locations.
The location is displayed on the screen, using a blue marker.

Read:
Top iOS Interview Questions And Answers for Beginners
iOS Interview Questions And Answers For 1-2 years Experienced Candidates.
iOS Interview Questions And Answers part 16
​iOS interview Questions And Answers Part 21