What is a pointer?
A variable
A memory address
that points to a specific object
An object that calls other objects
A class
If you do not declare a return type for a method definition, what is the default return type?
*NSString
id
No return type
What is the Allocations instrument used for?
Allows you to view your variable values
A debugging tool that frees up memory
Recording
information from a single process about memory allocation
what does this code produce? [NSString] *myString = @"Hello World";
An Error during
compile
makes the pointer to myString equal to the pointer
of the new created object with @"hello world"
gets SIGABRT while executing the application
it put the value Hello World into a string named myString
none of the above
How do you get the Unicode character set of a Core Text font?
CTFontCopyDisplayName
CTFontCopyCharacterSet
CTFontCopyFamilyName
True or False? A UIButton inherits from UIView.
True
False
Developers are allowed to call [super dealloc] in ARC.
TRUE
FALSE
What is the difference between methods that begin with + and -?
Instance methods
begin with - class level methods begin with +
+ methods are inheritable, - methods are not
+ methods are public, - methods are private
How can you declare a method, that can be set as the action to be performed on various events?
- (IBAction)
action:(id) sender;
-(SEL) action:(id) event;
-(selector) action:(id) sender;
What is KVO?
Key Variable Obfuscation
Key Value Operations
Key Value
Observing
What is a Category?
A category is a
way to extend a class by adding functions to it
A category is adding methods to a class where
pointers in the memory no longer exist for an instance of a class to execute
it.
A category defines a set of functions which a class
implements
One way to alter the destination of a message at
runtime by switching the implementations.
True or False? You can compare two strings by (string1 == string2)
True
False
To have an IOS app Screen Design we used which of the following tool?
None of above
Interface Xcode
Interface
builder
Interface Designer
Instruments
What does the "id" type mean?
This is the
general type for any kind of object regardless of class
This is a type for a specific object of class id
This is a type for strings
What is the method for adding KVO to your app?
addKVO:forKey:
addListener:withContext:andObject:
addObserver:forKeyPath:options:context
How do you concatenate two NSStrings *foo and NSString *bar to form a new NSString *baz?
baz = foo + bar;
baz = [foo
stringByAppendingString: bar];
baz = foo & bar;
baz = [foo appendString: bar];
baz = [foo concat: bar];
What framework does the class UIButton come from?
CoreGraphics
Foundation
EventKit
UIKit
OpenGLES
If you define a new class called Foo which inherits from NSObject, how do you create a new instance of it?
Foo *temp = new Foo();
Foo *temp = Make Instance of Foo;
Foo *temp =
[[Foo alloc] init];
Foo *temp = System.Create(Foo);
Foo *temp = [Foo init];
What does an Objective-C string literal look like?
"foo"
#"foo"
@"foo"
$"foo"
NSString("foo")
ARC means?
Automatic
Reference Counting
Angular Reference Courting
Access Reference Collation
Artificial Reference Counting
Application Reference Collection
Where is a MKAnnotationView used?
On a cell
In a button
On a Map View
On a table view
What is a delegate?
A delegate is a UIView
A delegate holds the type of data a variable stores
A delegate
allows one NSObject to send messages to another NSObject, and listen to those
messages
A delegate is a variable
Which of the following is a Singleton?
[NSArray array]
[NSFileManager
defaultManager]
Which of the following is an object?
double
NSNumber
int
float
What is the name of the type of SQL Database that iOS Supports?
SQL
NoSql
SQLite
MySql
What type of object is this under XCode 4.5: @[rabbit, chicken, owl]
SQLite schema
NSArray
NSString
NSDictionary
What does a CAEmitterCell do?
Nothing, it is not a valid class
It defines the
properties and direction of emitted particles from a CAEmitterLayer object.
It intercepts touch events
It is used by the GPS to track user coordinates and
returns to values as coordinates
What happens when you call retain on an object?
It is permanently stored in memory
It will stay in memory until the app closes
You increase its
retain count by 1
It is released from memory
How do you free an object?
[obj release]
None of the above
free(obj)
[obj dealloc]
[obj free]
How does KVO respond to change notifications?
respondToValueChange:forKey:
listenToChange:forObject:andContext:
observeValueForKeyPath:ofObject:change:context
What is a dependency in NSOperationQueue?
A dependency is
a way to have an operation wait to be performed until the dependencies have
been fulfilled/executed
A dependency sets the variables of the
NSOperationQueue
A dependency is the alloc/init method of the
NSOperationQueue
True or False? Sending a command asynchronously will lock the main thread and then wait until the command is finished before moving on to the next part of your code.
False
True
Which of the following accesses a variable in structure b?
b.var;
b-var;
b>var;
b->var;
b
If a class conforms to a protocol what must it do?
Implement all
methods in the protocol, except for optional ones
Implement all methods in the protocol without
exception
Implement all or some methods and leave the rest to
be implemented by subclasses
Implement all methods which do not have a default
implementation in the protocol
True or False? For an object to use constraints, it must have at least 3 constraint values.
False
True
What is used to sort Core Data results?
NSSort
NSCoreDataSort
[self sort]
NSSortDescriptor
True or False? A method and a variable can have the same name in Objective-C.
False
True
What is a design pattern?
A methodology for approching database design.
Coding standards used by an organization.
A template for a
solution to a common problem faced by programmers.
How can you add a new method foo to an existing class Bar?
Both "extend" options are correct.
It's not possible.
Send Bar the "extend:" message, e.g. [Bar
extend: foo].
Define a C function foo and then send Bar the
extend:withSelector: message, e.g. [Bar extend: foo withSelector:
@selector(foo:)].
Make a category,
e.g. @interface Bar(Foo).
Can you call C++ code from objective C environment?
Yes, from any
.mm file
Yes, from any .m file
No, it is not possible
What framework is KVO (key value observing) a part of?
Foundation
UIKit
CoreData
Assume ARC is enabled... What would be another way to write this: NSArray *array = [NSArray arrayWithObjects:@"One", @"Two", @"Three",nil];
NSArray *array = [@"One",
@"Two",@"Three"];
NSArray *array =
@[@"One", @"Two", @"Three"];
NSArray *array = {@"One",
@"Two",@"Three"};
NSArray *array = @{@"One",
@"Two", @"Three"};
let a:int=5 a=10 this code is true of false?
false
true
Does Objective-C have constructors and destructors?
Yes
It depends on the object
No, you use init
and dealloc on Objective-C
Only NSStrings do
What is the type of @selector(foo)?
id
selector
None, that is not a valid Objective-C expression.
SEL
What class supports the sharing of small amounts of data such as strings or dates to iCloud?
NSUrlConnection
NSOperation
NSUbiquitousKeyValueStore
Are integers full-fledged objects in Objective-C?
Yes, but only if you first cast them as id's, e.g.
(id) 123.
No, they are not
objects at all.
Integers are only partial objects in Objective-C
(e.g. do not support any user defined methods).
Yes.
Using UIViewController containment, which one of the following statements is true:
The root
viewcontroller handles loading and unloading its child viewcontrollers.
Every viewcontroller can handle the loading and
unloading of other viewcontroller.
What is the difference between [Foo new] and [[Foo alloc] init]?
New will not always initialize the object.
New is significantly faster than alloc + init.
None, they
perform the same actions.
New does not exist in Objective-C.
What is one source of particles that are emitted by a CAEmitterLayer object?
A UIEmitterView
A NSEmitter
A CAEmitterCell
What is the 'print object' command in the debugger window?
print
p
-l
po
What happens at runtime with the following: NSObject* object = nil; NSObject* object2 = [object copy]; NSLog(@"%@", object2);
Application crashes with "SIGABRT: object has
been derferenced" error
Application continues, but issues "cannot
access nil object reference" warning
object2 is instantiated as an NSObject with nil
values
Log prints
"(null)" and continues as usual.
What is @dynamic directive meaning in iOS?
The @dynamic directive generates the accessor
methods for you at compile time.
The @dynamic
directive tells the compiler that you will provide accessor methods dynamically
at runtime.
The @dynamic directive generates getter method for
your property at compile time.
The @dynamic directive generates setter method for
your property at compile time.
What class will allow you to use one or more blocks concurrently?
NSBlockOperation
NSConcurrentBlock
NSConcurrency
NSBlock
In Core Data, what is the name of an object representation of a record?
NSManagedObjectModel
NSManageObjectContext
NSManagedObject
NSEntityDescription
What is Objective-C's language design based on?
C and C++.
C and Cocoa.
C and Smalltalk.
C and BCPL.
C and Objectivity.
True or False? You should use NSHost when connecting to a specific host.
True
False (You
should use CFHost)
What is the difference between #import and #include ?
#import ensures
that a file is only ever included once, and #include allows the same file to be
inlcuded many times.
None, they do the same thing.
#include is not valid syntax
#include ensures that a file is only ever included
once and #import permits the file to be included many times.
True or False? Strings are one of the most common sources of buffer overflow attacks.
True
False
True or False? You can use %@ to specify a dynamic property.
True
False
What is a proper format for calling an asynchronous function?
[dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND,
0), // code ];
[NSOperationDispatchAsync dispatch_asyncWithBlock:
^{ // code }];
[dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND,
0), ^{ // code })];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND,
0), ^{ // code });
True or False? You can perform operator overloading in Objective-C.
False
True
What are the two types of predicates?
Expression and Operator
Comparison and
Compound
Filter and Exclusion
What is a persistent object store?
It represents an
external file of persisted data
It is the relationships between tables in your data
It is the schema for your object
It is retained database objects
The proper typedef syntax for an Objective-C block that takes an NSArray and returns an NSString is
typedef aBlock^ = (NSString *)(NSArray *);
typedef NSArray *(^aBlock)(NSString *);
typedef void(^aBlock)(void);
typedef NSString
*(^aBlock)(NSArray *);
How do you convert a Core Image color to a UIColor?
UIColorWithCIColor:
UIColorValue:
CIColorValue:
colorWithCIColor:
How can you temporarily disable layer actions in a Core Animation?
Using the
CATransaction class
Using the CAStopAnimation class
Using the CAExit class
Using the CAStop class
What can happen if you use self inside a block?
None of the above
self can become a dangling pointer
You can create a
retain cycle
By the time the block executes, self can be
pointing to a different object
True or False? The format for a NSPredicate is the same as a Regular Expression.
False
True
Objective-C methods with certain names (“init”, “alloc”, etc.) always return objects that are an instance of the receiving class’s type; such methods are said to have a “related result type”. A method with a related result type can be declared by using:
returntype
id
resultType
instancetype
NSRelatedType
In Core Data, what is the name of the object representation for the database schema?
NSManageObjectContext
NSManagedObjectModel
NSEntityDescription
NSManagedObject
Which framework lets you determine the current location or heading associated with a device?
CFLocation
MapKit
LocationKit
CoreLocation
NSLocation
What is (void*)0 ?
Representation of void pointer
None of above
Representation
of NULL pointer
Error
What protocol is used to create an action object?
CoreAnimation
CAAction
NSAction
None of These
Which of these classes is NOT a root class?
NSString
NSMessageBuilder
NSObject
NSProxy
NSZombie
True or False? Key value coding is used to indirectly access an object's attributes using indexes.
True
False
What is the object.toString equivalent in objective-c?
[NSObject toString]
[NSObject
description]
[NSObject stringWithFormat]
[NSObject getDescription]
[NSObject getDetails]
What does the following code do, assume ARC is enabled? NSArray *myArray; for (int i = 0; i < 10; i++){ @autoreleasepool { myArray = [[NSArray alloc]init]; } }
For each
iteration of the loop a new array is allocated and released.
For each iteration of the loop a new array is
allocated and will be released at the end of the loop.
For each iteration of the loop a new array is
allocated only.
For each iteration of the loop a new array is
allocated and will leak memory.
What happens if you use fgets and do not give it a size smaller than the buffer?
It will use the size of the object as its size
It will
overwrite the data past the size
It will clip its size automatically
None of these
how can we return multiple values from function?
not possible
void*
tuple
If you wanted to override the default alloc method in a class Foo, what would be the appropriate way to declare it?
- (Foo *) alloc;
+ (Foo *) alloc;
+ (id) alloc;
It's not possible to override alloc.
- (id) alloc;
What is not supported in Objective-C
Recursive method call
Method argument
default value
Variable argument count to method
Byte manipulation
What class method is used to make an NSArray from NSData class?
NSArray arrayWithObject:
NSFileManager defaultManager
NSData dataWithContentsOfFile:
NSKeyedUnarchiver
unarchiveObjectWithData:
What do you use for an outgoing TCP connection?
NSStream
NSTCPProtocol
(none of these)
NSUrlStream
Which method, if defined, is guaranteed to be called once -- and only once -- when a class is first referenced?
+ (id) alloc;
+ (void) init;
+ (id) init;
+ (Class) alloc;
+ (void)
initialize;
Which of these property declaration attributes does not specify setter semantics?
strong
assign
nonatomic
weak
copy
What can you say about the code: NSString * str = [NSString stringWithFormat:@""]; [str release];
it will cause a SIGABRT when the enclosing method
ends
It will cause
the string to be released twice with undefined consequences when the
surrounding autorelease pool is emptied
It will cause a SIGSEGV at [str release];
None of these
It is correct, everything will work fine
How do you add a brightening effect on a CoreImage?
Set the alpha
CIBrighten
CIAdditionCompositing
Which of these methods is NOT invoked by the runtime itself?
-forwardInvocation:
+load
+initialize
-dealloc
-doesNotRecognizeSelector:
What is the last chance for an object to handle a message?
-forwardInvocation:
-forwardingTargetForSelector:
-respondsToSelector:
+resolveInstanceMethod:
+instancesRespondToSelector:
A UITableViewController's tableview must have its delegate explicitly set by the developer.
TRUE
FALSE
What's the difference between nil and NULL?
nil is literal null value for Objective-C
instances. NULL is object used to represent null
nil is literal null value for Objective-C
instances. NULL is literal null value for Objective-C classes
nil is literal
null value for Objective-C instances. NULL is literal null value for C pointers
NULL is literal null value for Objective-C
instances. nil is literal null value for C pointers
they are the same thing
How is a selector typically represented in memory?
As a pointer to a C struct.
As a unique 32-bit number.
As a null
terminated C string.
As an Objective-C object.
A UIView is a superclass of:
UIViewController
UIWindow
UIImage
UILabel
UIScreen
What are @try and @catch?
Exception
keywords
All of these
Exception handlers
Exceptions
How to restore Consumable In-App Purchases?
Use Store Kit’s finishTransaction: method
Consumable
In-App Purchases are not to be restored
Use Store Kit’s addPayment: method
Use Store Kit’s initWithProductIdentifiers: method
Use Store Kit’s restoreCompletedTransactions method
What happens at runtime with the following: NSMutableString *tempString = [NSMutableString stringWithString:@"1"]; dispatch_sync(dispatch_get_main_queue(), ^{ [tempString appendString:@"2"]; NSLog(@"%@", tempString); }); [tempString appendString:@"3"];
Log prints "132" and continues as usual.
Log prints "12" and then we will have a
deadlock here because the main queue will block
Log prints "123" and continues as usual.
Log doesn't
print anything. It's a deadlock here because the main queue will block on the
call to dispatch_sync
What сan you use to avoid msgSend function overhead?
None of these
IMP
SEL
You can't use anything
Which of the following statements is correct?
@property(readwrite,retain,atomic)NSInteger
value;
@property(readwrite,copy,atomic)NSInteger value;
@property(readwrite,retain,atomic,copy)NSInteger
value;
@property(readwrite,assign,copy,atomic)NSInteger
value;
none of the above
What happens at runtime with the following: dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_apply(10, queue, ^(size_t index) { NSLog(@"%zu", index); });
Log prints "0123456789"
We won't have
persistent result
Log prints "12345678910"
Log prints "9876543210"
