Objective-C Style Guide

This is the style guide that I follow when programming in Objective-C, this is for my own reference, but other people may find this useful.

General

  • Use modern objective-c 2.0 syntax
  • Use ARC whenever possible.
  • Manual memory management should only be used when using older libraries that haven’t been updated yet.
  • Use tabs when indenting, not spaces.

Code Naming Basics

  • Follow the Apple naming guidelines
  • Use descriptive names, even if they are long. Xcode has great code completion features. Use them.
    • Clarity is preferred over all else.
    • E.g. Compare the two methods: [spaceship fly: 10.0f] and [spaceship flyAtSpeed: 10.0f].
    • Note how much clearer the second declaration is, the method describes its intentions and parameter names.
  • Don’t use abbreviations. E.g. bgColor vs. backgroundColor
  • Custom resuseable classes should be prefixed with AFG
    • Application level classes do not have to be prefixed. E.g. ViewControllers
  • All view controllers should be descriptively named and end with ViewController.
    • E.g. CalculatorSettingsViewController

Commenting

  • Follow the appledoc code formatting style.
  • Only comment the method declarations. E.g. In the @interface or private @interface ... () code blocks.
  • Describe what the method does, the parameter names and the return value and what it signifies. The following is a good example of method commenting:
/** This method asks the delegate if the AFGContainerViewController should pop the current view from the view stack.
 @param - The current AFGContainerViewController object
 @return A BOOL value indicating if the current view controller should be removed from the AFGContainerViewController's view stack.
 */
-(BOOL) AFGContainerViewControllerShouldPopContainerViewController: (AFGContainerViewController*) containerViewController;

Spacing

-(void) performOperationWithObject: (NSObject*) objectName {

  NSLog(@"This is a well spaced method");
  [objectName performSomeOperation];
}
  • No space between the class or instance specifier (+,-)
  • Single space between the return type and method name
  • Single spaces between method signature, object types and object names
  • Brace on the same line as the method signature.
  • Optional newline below the method signature for readability
  • No newline before the closing brace

Variables and Initializers

  • Variable names should always start with lower case.
    • Good: numberOfObjects
    • Bad: NumberOfObjects
  • Clearly identify the designated initializer for the class
    • All other initializers should propagate up to and use the designated initializer.
  • Override the superclass’ designated initializer.
  • Initialization method should be at the top of the @implementation
  • Don’t explicitly initialize variables to nil. Under ARC this happens automatically.

Properties

  • Don’t @synthesize properties. ARC does this automatically.
  • Always start with a lower case letter.
  • NSString properties should always be copy
  • IBOutlets should always be weak

Other readings

These are some good references / starting points for creating your own style guide or just to see other coding styles.

Advertisements