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Objective-C Basics

Some basic information about the development language for native iOS applications
STUDY
PLAY
Objective-C is a _____ of the C language
superset
Objective-C borrows much of its syntax from ______, one of the earliest object-oriented languages
Smalltalk
Objective-C binds methods and arguments at _____ instead of _______ time
runtime...compile
KVC
Key-value coding
KVO
Key-value observing
There are ____ fundamental building blocks in Objective-C
9
The nine fundamental building blocks of Objective-C can be dividing into 2 categories: _____ and _______
data...procedures
Data (like nouns) represent the information we are processing and in Objective-C this made up of the four elements of _____, _____, _____, and ______
C types, structures, enums, and objects
Procedures (like verbs) are processes that manipulate or transform data, and in Objective-C these 3 elements are _____, ______, and _____
C operators, functions, and methods
Two additional foundational building blocks of Objective-C distinct from data and procedure type foundations
Protocols and Categories/Extensions
Data types are divided into two main categories: _____ and ______
integer and floating-point
7 Common Integer data types
BOOL, char, short, int, long, long long, NSInteger
3 Common Float data types
float, double, CGFloat
Integer data types come in _____ and _____ variants
signed and unsigned
_____ data types can be both positive and negative, while ______ data types are always zero or greate
Signed...unsigned
True or false: In Objective-C, floats are more commonly used that doubles
true
What is the intention of the Objective-C command: typedef double NSTimeInterval;
Sets an 'alias' for double to better communicate the intent of a section of code.
Three main categories of more complicated data structures (beyond simple or 'primitive' data types)
pointers, arrays and structs
A variable that points to the memory address of another value
pointer
_____ allow indirect access and modification of a variable's value.
Pointers
Pointers are declared by placing a(n) ___ between the type declaration and the variable name
asterisk (*)
The process of setting or reading the value at an address pointed to by a pointer
dereference (dereferencing)
Placing a(n) ____ before a normal variable name gives it's address
ampersand (&)
What is the result of the following code: int a=10; int b=&a; b=15;
Changes the value of a to 15
Write an Objective-C statement to create an array named myList to hold 10 integers
int myList[10];
The first index in an array is valued at ____
zero
Write an Objective-C statement to create a literal array of integers named fibo containing 1, 1, 2, 3, 5
int fibo[ ] = {1,1,2,3,5};
C-style strings always end with a ____ character
null
C-style strings are stored in an array of _____
chars
True or false: char s1[5] = "test"; is a correct declaration/initialization for a C-style string
true (C appends a null value automatically)
Rather than using arrays in Objective-C, we often are able to use it's collection classes of ____, ____ and _____ with _____ for strings
NSArray, NSSet and NSDictionary with NSString
The most flexible C data type: ______
struct
A struct may contain multiple ____ consisting of ______ data types
fields...different
Create a CGRect object called r3 with an origin (top-left corner) of (100, 200), a width of 10 and a height of 20 using a struct literal formulation
CGRect r3 = {{100,200}, {10, 20}};
Create a CGRect object called r3 with an origin (top-left corner) of (100, 200), a width of 10 and a height of 20 using a helper function formulation
CGRect r3 = CGRectMake(100, 200, 10, 20);
If you are compiling an application with ARC, you _____ store Objective-C objects inside a _____
cannot...struct
ARC
Automatic Reference Counting
A compiler feature that provides automated memory management
ARC
____ provide a concise, elegant method for defining a discrete set of values
Enumerations
In the correct statement: int a = 5; 'int' is the ______, 'a' and '5' are the _______ and '=' is the ______. 'a' is known as the variable _______
datatype, operands, assignment operator, identifier
The 6 main categories of operators are: ____, _____, _____, ______, _______ and _______
assignment, arithmetic, comparison, logical, bitwise and membership
______ operators take a single operand
Unitary
_____ operators take 2 operands
Binary
a++; is an example of using a _____ operator
unitary
a+b; is an example of using a _____ operator
binary
Given: if(n % 2 == 0)isEven = YES; else isEven = NO; Rewrite using a ternary operator formulation
isEven = (n%2 == 0)? YES : NO;
In computer science, the mathematical concept of "order of operations' is known as the "order of ______"
precedence
The _____ function can be used to print a message to the console
printf( )
Symbol used to denote a placeholder in a format string
%
In C, all functions pass their arguments by ____, which means the compiler makes local copies of those arguments
value
In a home building analogy, a ____ is the blueprint and the _____ is the house
class...object
_____ is one of the main advantages of object-oriented code and allows objects to 'hide away' much of their complexity, operating at times like a proverbial 'black-box'.
Encapsulation
A _______ method is one that is likely to be unsupported in the future (although it may work in the present). It's use should be discontinued.
deprecated
The root class in Objective-C
NSObject
Objective-C methods are called using ____ _____
square brackets
In a format string, the place holder for an object is ______
%@
Instance variables are ________ in iOS if ________ are used
optional...properties
When creating a class header file, you begin with the _____ keyword and close with the _____ keyword
@interface...@end
When creating a class implementation file, you begin with the _____ keyword and close with the _____ keyword
@implementation...@end
True or false: When declaring 'id' variables, we do not use an asterisk since the 'id' type is already defined as a pointer to an object
true
Square bracket syntax for calling a method
[receiver message];
Consider: [NSString alloc]. 'alloc' is an example of a(n) ______ method rather than a(n) _______ method
class...instance
This symbol denotes a method as being an instance method
-
This symbol denotes a method as being a class method
+
Initializer method traditionally begin with the _____ prefix
init
Each class should have a ______ initializer, a single method responsible for performing all of the object's setup and initialization. Typically it is the initializer with the largest number of arguments.
designated
Property attribute that synthesizes accessors that are not thread safe
nonatomic
Property attribute that synthesizes both a getter and setter for the property
readwrite
Property attribute that synthesizes only a getter for the property
readonly
Property attribute that causes the setter to store a copy of the assigned value
copy
Property attribute that causes the setter to store a zeroing weak reference to the assigned value
weak
Property attribute that causes the setter to store a strong reference to the assigned value
strong
Property attribute where the setter stores the assigned value but does not perform any memory management. Should only be used for storing non-object data (int, float, etc). Objective-C objects should use strong or weak attributes instead
assign
Objective-C's protocols are really about communicating _____ _______
developer intent
Protocols are adopted by adding a _____- _______ list of protocols inside _____ ______ after the _______ _________ in a class's _______ block
comma-separated....angled brackets... superclass declaration....@interface
_____ allow you to add new methods to existing classes.
Categories
A ____ ____ is a situation where you free memory and then accidentally continue to use it
dangling pointer
A ____ _____ is where you forget to free up memory
memory leak
All objects are created on the _____
heap
ARC is susceptible to ____ _____
retain cycles
A retain cycle occurs when...
...two objects directly or indirectly refer to each other using strong references.
Zeroing weak referencing should be used for _____ and _____ to prevent inadvertent retain cycles
delegates ... data sources
Xcode sequence to convert non-ARC apps to ARC
Edit>Refactor>Convert to Objective-C ARC
Xcode sequence to examine an app for memory leaks or retain cycles
Product>Profile>Leaks>Profile
Given: [graduationParty addAttendee: @"Aunt Jane" withDish: @"deviled eggs"]; The 'receiver' is _______; the 'selector' is _________; the 'argument(s)' is(are) _______
graduationParty...addAttendee:withDish...@"Aunt Jane" & @"deviledEggs"
Given: a Java command: graduationParty.addAttendeeWithDish("Aunt Jane", "deviled eggs"); Re-write in Objective-C.
[graduationParty addAttendee: @"Aunt Jane" withDish: @"deviled eggs"];
To destroy an object, set the variable that points to it to _____
nil
Alternative code for: if(venue == nil){[organizer remindToFindVenueForParty];}
if(!venue){[organizer remindToFindVenueForParty];}
To create a "Command Line Tool" type project from a template you must choose _____ from the ______ menu in the template selection area
Application...Mac OS X
Correct the error: NSMutableArray items = [[NSMutableArray alloc] init];
Replace 'items' with '*items'
Correct the error: NSMutableArray items = [[NSMutableArray init] alloc];
Swap the locations of init and alloc
NSMutableArray *items = [[NSMutableArray alloc] init]
Add a semicolon to the end of the message
Rewrite as a 'foreach' construction:for(int i = 0; i < [items count]; i++){NSLog(@"%@", items objectAtIndex:i]);} Use an NSString called 's' as the variable.
for(NSString *s in items){ NSLog(@"%@", s)};