cocoa-conventions: A repository from Lejdborg

These guidelines build on Apple's existing Coding Guidelines for Cocoa. Unless explicitly contradicted below, assume that all of Apple's guidelines apply as well.

This styleguide is based on GitHub's Objective-C conventions, but we don't agree on everything :)

Whitespace

Indent blocks using 4 spaces
Activate "Automatically trim trailing whitespace" and "Including whitespace-only lines" in Xcode settings -> Text Editing.
Make liberal use of vertical whitespace to divide code into logical chunks.
Blocks are separated by one, and only one, empty line.

Documentation and Organization

All method declarations should be documented using the AppleDoc standard.
Comments should be hard-wrapped at 80 characters.
Use #pragma marks to categorize methods into functional groupings and protocol implementations, following this general structure:

// -----------------------------------------------------------------------------
#pragma mark - TABLE VIEW DELEGATE
// -----------------------------------------------------------------------------

Use the same groupings in header files, but format them according as AppleDoc:

/// ----------------------------------------------------------------------------
/// @name Table View Delegate
/// ----------------------------------------------------------------------------

Declarations

Always prefer properties to ivars.
Prefer exposing an immutable type for a property if it being mutable is an implementation detail. This is a valid reason to declare an ivar for a property.
Don't use @synthesize unless the compiler requires it. Note that optional properties in protocols must be explicitly synthesized in order to exist.
Instance variables should be prefixed with an underscore (just like when implicitly synthesized).
Don't put a space between an object type and the protocol it conforms to.

@property (attributes) id<Protocol> object;

C function declarations should have no space before the opening parenthesis, and should be namespaced just like a class.

void NMAwesomeFunction(BOOL hasSomeArgs);

Expressions

Don't access an ivar unless you're in -init, -dealloc or a custom accessor.
Use dot-syntax for getters, but not setters:

[self.manager setDelegate:self];

Use object literals, boxed expressions, and subscripting over the older, grosser alternatives.
Comparisons should be explicit for everything except BOOLs.
Prefer positive comparisons to negative.
Long form ternary operators should be wrapped in parentheses and only used for assignment and arguments.

Blah *a = (stuff == thing ? foo : bar);

Short form, nil coalescing ternary operators should avoid parentheses.

Blah *b = thingThatCouldBeNil ?: defaultValue;

There shouldn't be a space between a cast and the variable being cast.

NewType a = (NewType)b;

Control Structures

Always surround if bodies with curly braces.
All curly braces should begin on the same line as their associated statement. They should end on a new line.
Else statements should begin on a new line.
Put a single space after keywords and before their parentheses.
Return and break early.
No spaces between parentheses and their contents.

if (something == nil) {
    // do stuff
}
else {
    // do other stuff
}

Literals

Avoid making numbers a specific type unless necessary (for example, prefer 5 to 5.0, and 5.3 to 5.3f).
The contents of array and dictionary literals should have a space on both sides.
Dictionary literals should have no space between the key and the colon, and a single space between colon and value.

NSArray *numbers = @[ @1, @2, @3 ];
NSDictionary *prefs = @{ @"FollowConventions": @YES };

Longer or more complex literals should be split over multiple lines (and never have a terminating comma):

NSArray *theShit = @[
    @"Lorem ipsum and stuff...",
    @"And the quick brown fox",
    @"They should be friends"
];