iPhone interview questions(Basic-2)

8.What are the location services? 

Location Services allows applications such as Maps, Camera, and Compass to use information from cellular, Wi-Fi¹, and Global Positioning System (GPS) networks to determine your approximate location. This information is collected anonymously and in a form that does not personally identify you.  More Detail 

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9.How would you create your own custom view?

By Sub-classing the UIView class.

10.Whats fast enumeration?

Fast enumeration is a language feature that allows you to enumerate over the contents of a collection. (Your code will also run faster because the internal implementation reduces
message send overhead and increases pipelining potential.)

11.Explain retain counts.

Retain counts are the way in which memory is managed in Objective-C. When you create an object, it has a retain count of 1. When you send an object a retain message, its retain
count is incremented by 1. When you send an object a release message, its retain count is decremented by 1. When you send an object a autorelease message, its retain count is decremented by 1 at some
stage in the future. If an objectʼs retain count is reduced to 0, it is deallocated.

12.Whats the difference between  NSArray and  NSMutableArray?




NSMutableArray (and all other classes with Mutable in the name) can be modified. So, if you create a plainNSArray, you cannot change its contents later (without recreating it). But if you create an NSMutableArray, you can change it — you'll notice it has methods like -addObject: and -insertObject:atIndex:.more Details are here

13.Whats a struct?

A struct is a special C data type that encapsulates other pieces of data into a single cohesive unit. Like an object, but built into C.More

14.Whats the difference between frame and bounds?

The frame of a view is the rectangle, expressed as a location (x,y) and size (width,height) relative to the superview it is contained within. The bounds of a view is the rectangle, expressed as a location (x,y) and size (width,height) relative to its own coordinate system (0,0).