Types

short, int, long, NSInteger

Represent integers. short holds smaller numbers than int, which is smaller than long. NSInteger is a type provided by Apple that is an integer of the ideal size for the current platform, be it iOS or OS X.

float, double, CGFloat

Decimal numbers, double is capable of storing higher precision numbers than float, but uses up double the storage space. CGFloat is the decimal type used by the iOS Core Graphics framework.

Pointer

Pointers are variables that "point" to other variables. In Objective-C, we never deal with objects directly, but instead pass around pointers to them. This is why when we declare an object, the variable that we store is a pointer to the object.
NSDate *today = [NSDate date];
Technically we say that "today is a pointer to an NSDate," however since objects are always stored as pointers, normally you will just say that "today is an NSDate."

struct

Structures are composite types. They allow us to group together data into a more complicated concept. For example I want a type Location that knows the name, latitude, and longitude of a location and the number of times I had visited that place.

typedef struct {
  float latitude;
  float longitude;
  int visits;
} Location;
    

Elements of a struct are accessed using dot notation.

Location theFactory;
theFactory.latitude = 42.963107; 
theFactory.longitude = -85.669407;
theFactory.visits = 42;

Structs are used frequently in iOS development. Try looking up NSRect in the XCode documentation. NSRects are used to represent the location of a user interface element

BOOL

Boolean values, takes two values, YES or NO.

Format Strings

Integers

%i

Decimals (floats)

%f

NSString

%@

NSString *name = @"The Tempest";
float height = 1.75;
int age = 42;
NSLog(@"%@ is my favorite Shakepear play", name);
NSLog(@"You must be at least %f meteres tall to ride this ride", height);
NSLog(@"That person over there is %i years old", age);

Functions

rtype functionName(type1 arg1, type2 arg2)

Including Libraries

#import <math.h>  // Angle brackets for accessing built-in functions
#import "MyAwesomeUtility.h" // Quotes for accessing user functions

Conditionals

if (condition) {
  // Do if condition is true
} else {
  // Do if condition is false
}

Loops

While

while (condition) {
  // Run this as long as condition is true
}

For

for (initialize; test; increment) {
// Run this as long as test passes, preform increment 
// at the end of every loop
}