Objective-C

#import "AnyHeaderFile.h"

@interface MyClassName : SuperClassName
// define public properties
// define public methods
@end

#import "MyClassName.h"

@interface MyClassName ()
// define private properties
// define private methods
@end

@implementation MyClassName {
// define private instance variables
}

// implement methods

@end

type myVariableName;

int
1, 2, 500, 10000

float, double
1.5, 3.14, 578.234

BOOL
YES, NO

ClassName *
NSString *, NSArray *, ...

id
Hold reference to any object (no need to add *)

@property (attribute1, attribute2, ...) type myPropertyName;

Automatically defines a private instance variable

type _myPropertyName;

Automatically creates a getter and setter

- (type)myPropertyName;
- (void)setMyPropertyName:(type)name;

Using _myPropertyName uses the private instance variable directly.
Using self.myPropertyName uses the getter and setter.

strong
Adds reference to keep object alive

weak
Object can disapear, become nil

assign
Normal assign, no reference

copy
Make copy on assign

nonatomic
Make not threadsafe, increase performance

readwrite
Create getter & setter (default)

readonly
Create just getter

- (type)doIt;
- (type)doItWithA:(type)a;
- (type)doItWithA:(type)a andB:(type)b;

- (type)doIt {
    // do something
    return ReturnValue;
}

- (type)doItWithA:(type)a {
    // do something with a
    return ReturnValue;
}

- (type)doItWithA:(type)a andB:(type)b {
    // do something with a and b
    return ReturnValue;
}

  static const double name = value;
  static NSString * const name = value;

  // .h
  extern const double name;
  // .m
  const double name = value;

  // .h
  extern NSString * const name;
  // .m
  NSString * const name = value;

ClassName *myObject = [[ClassName alloc] init];

// setting value
[myObject setMyPropertyName:a]; // or
myObject.myPropertyName = a;

// getting value
a = [myObject myPropertyName]; // or
a = myObject.myPropertyName;

[myObject doIt];
[myObject doItWithA:a];
[myObject doItWithA:a andB:b];

- (id)initWithParam:(type)param {
    if ((self = [super init])) {
        _myPropertyName = param;
    }
    return self;
}

NSString *personOne = @"Ray";
NSString *personTwo = @"Shawn";
NSString *combinedString = [NSString stringWithFormat:@"%@: Hello, %@!", personOne, personTwo];
NSLog(@"%@", combinedString);
NSString *tipString = @"24.99";
float tipFloat = [tipString floatValue];

NSMutableArray *array = [@[person1, person2] mutableCopy];
[array addObject:@"Waldo"];
for (NSString *person in array) {
    NSLog(@"Person: %@", person);
}
NSString *waldo = array[2];