61⟩ What is "notification"?
provides a mechanism for broadcasting information within a program, using notification we can send message to other object by adding observer .
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102 IOS Developer Questions And Answers
62⟩ What is meaning of "readOnly" keyword?
Declare read only object / declare only getter method
63⟩ How to start a selector on a background thread?
- (void)performSelectorInBackground:(SEL)aSelector withObject:(id)arg on NSObject
64⟩ Explain me App Bundle?
During iOS application development, Xcode packages it as a bundle. A Bundle is a file directory that combines related resources together in one place. It contains the Application Executable File and supports Resource Files such as Localized Content, Image Files and Application Icons.
65⟩ Do you know which JSON Framework is supported by iOS?
SBJSON is the framework that is supported by iOS. It is a generator and a JSON Parser for Objective-C. SBJSON provides flexible APIs and also makes JSON handling easier.
66⟩ Does iOS supports Multi-Tasking functionality?
Multi-Tasking functionality is supported from iOS versions 4 and the later ones. Multi-Tasking is a feature that enables applications to remain in the background until it is re-launched or terminated.
67⟩ What framework is used to construct application’s iOS User Interface?
The UIKit framework is the Framework that is used to develop application’s User Interface for iOS. UIKit framework provides Views, Drawingg Model, Controls, Event Handling, Windows specifically designed for a touch screen interface.
68⟩ Please explain what is difference strong and weak reference?
complier with be responsible for lifetime of object which is declared as strong. for weak object - compiler will destroy object once strong reference that hold weak object get destroyed.
69⟩ Explain steps for using coredata?
NSFetchedResultsController - It is designed primarily to function as a data source for a UITableView
70⟩ Explain differentiate between Release and Pool Drain?
The release keyword is used to free a memory location in the system which is not being utilized. The drain keyword is used to release the NSAutoreleasePool.
71⟩ What is meaning of "synthesize" keyword?
ask the compiler to generate the setter and getter methods according to the specification in the declaration
72⟩ Explain me what is "Delegate"?
A delegate is an object that will respond to pre-chosen selectors (function calls) at some point in the future., need to implement the protocol method by the delegate object.
73⟩ Explain Layer Objects?
Layer Objects are Data Objects that represent the Visual Content. They are used to render the Content. Layer Objects can be customized and these custom layer objects are used to implement Complex Animations and other types of sophisticated Visual Effects.
74⟩ Explain me how to parse xml?
Using NSXMLParser.
Create xml parser object with xml data, set its delegate , and call the parse method with parserObject.
Delegate methods getting called :
☛ – parserDidStartDocument:
☛ – parserDidEndDocument:
☛ – parser:didStartElement:namespaceURI:qualifiedName:attributes:
☛ – parser:didEndElement:namespaceURI:qualifiedName:
☛ – parser:didStartMappingPrefix:toURI:
☛ – parser:didEndMappingPrefix:
☛ – parser:resolveExternalEntityName:systemID:
☛ – parser:parseErrorOccurred:
☛ – parser:validationErrorOccurred:
☛ – parser:foundCharacters:
☛ – parser:foundIgnorableWhitespace:
☛ – parser:foundProcessingInstructionWithTarget:data:
☛ – parser:foundComment:
☛ – parser:foundCDATA:
75⟩ How to start a thread?
- (void)performSelectorInBackground:(SEL)aSelector withObject:(id)arg on NSObject
NSThread* evtThread = [ [NSThread alloc] initWithTarget:self
selector:@selector( saySomething )
object:nil ];
[ evtThread start ];
76⟩ What are Selectors in Objective-C?
A Selector in Objective C can be used to refer the name of a method when it is used in a Source-Code message to an Object. It also refers to the unique identifiers that can replace the Name when the Source Code is being Compiled. All the methods that have the same name have the same selector.
77⟩ Explain the difference between Cocoa and Cocoa Touch?
Cocoa is an Application Framework that enables development of Applications in Mac OS X Environment. It is basically a combination of two Frameworks i.e., Appkit Framework and Foundation Framework. Cocoa Touch is an Application Framework for iPod Touch. Iphone and iPad. It includes the Foundation Framework and UIKit Framework.
78⟩ What is "Protocol" on objective c?
A protocol declares methods that can be implemented by any class. Protocols are not classes themselves. They simply define an interface that other objects are responsible for implementing. Protocols have many advantages. The idea is to provide a way for classes to share the same method and property declarations without inheriting them from a common ancestor
79⟩ Explain me how to parse JSON?
By using NSJSONSerialization.
For example : NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutableContainers error: &e];
80⟩ What is Objective c?
*Objective-C is a reflective, object-oriented programming language which adds Smalltalk-style messaging to the C programming language. strictly superset of c.
