Introduction

This style guide outlines the common coding conventions of the iOS Developers.

Table of Contents

• Spacing
• Comments

Spacing

• Indent must use 4 spaces. Be sure to set this preference in Xcode (defaults is 4 spaces).

• Method braces and other braces (if/else/switch/while etc.) must open on the same line as the statement. Braces must close on a new line.

  For example: Objective-c

  if (user.isHappy) {
      // Do something
  }
  else {
      // Do something else
  }

  Swift

  if user.isHappy == true {
      // Do something
  }
  else {
      // Do something else
  }

• Separate imports from the rest of your file by 1 space. Optionally group imports if there are many (but try to have less dependencies). Include frameworks first.

  For example: Objective-c

  #import <AwesomeFramework/AwesomeFramework.h>
  #import <AnotherFramework/AnotherFramework.h>
  
  #import "SomeDependency.h"
  #import "SomeOtherDependency.h"
  
  @interface MyClass

  Swift

  import AwesomeFramework
  import AnotherFramework
  
  class MyViewController: UIViewController {
      // class stuff here
  }

• In Objective-C, use one empty line between class extension and implementation in .m file.

  @interface MyClass()
  
  // Properties - empty line above and below
  
  @end
  
  @implementation MyClass
  
  // Body - empty line above and below
  
  @end

• When using pragma marks leave 1 newline before and after.

  For example: Objective-c

  - (void)awakeFromNib {
      [super awakeFromNib];
      // something
  }
  
  #pragma mark - Config Cell
  
  - (void)configCell {
      // something
  }

  Swift

  override func awakeFromNib() {
     super.awakeFromNib()
     // somthing
  }
  
  // MARK: -  Config Cell
  
  func configCell() {
     //something
  }

• Prefer using auto-synthesis. But if necessary, @synthesize and @dynamic must each be declared on new lines in the implementation.

• There should be exactly one blank line between methods to aid in visual clarity and organization.

• Whitespace within methods should separate functionality, but often there should probably be new methods.

• When doing math use a single space between operators. Unless that operator is unary in which case don't use a space. For example:

  index = index + 1;
  index++;
  index += 1;
  index--;

• Colon-aligning method invocation should often be avoided. There are cases where a method signature may have >= 3 colons and colon-aligning makes the code more readable. Please do NOT however colon align methods containing blocks because Xcode's indenting makes it illegible.

  Good:

  objective-c

  // blocks are easily readable
  [UIView animateWithDuration:1.0 animations:^{
      // something
  } completion:^(BOOL finished) {
      // something
  }];

  swift

  UIView.animate(withDuration: 1.0, animations: {
      // something
  }, completion: { finished in
      // somthing
  })

  Bad:

  objective-c

  // colon-aligning makes the block indentation wacky and hard to read
  [UIView animateWithDuration:1.0
                   animations:^{
                       // something
                   }
                   completion:^(BOOL finished) {
                      // something
                   }];

  swift

  UIView.animate(withDuration: 1.0, 
                   animations: {
                      // something
                   }, completion: { finished in
                      // somthing
                   })

Comments

• When they are needed, comments should be used to explain why a particular piece of code does something. Any comments that are used must be kept up-to-date or deleted.
• Avoid block comments inline with code, as the code should be as self-documenting as possible. Exception: This does not apply to those comments used to generate documentation.

Developing....

References

• raywenderlich.com Objective-C style guide
• NYTimes Objective-C style guide
• Robots and Pencils Objective-C style guide