Objective C: How to view code in iOS

I am a new user on Stack Overflow and I am also an iOS developer. I want to know how to view our code?

What is a coding naming convention? What are the guidelines for variable name, class name. How can we do this?


source to share

2 answers

Apple has developed a set of guidelines for how to write code for maximum clarity and integration with wireframes. In addition, there are some undocumented conventions that Cocoa developers often use.

Class names:

  • Class names are always capitalized.

  • Objective-C has no namespaces, so prefix your class names with initials. This avoids "namespace collisions," which is a situation where two pieces of code have the same name but do different things. Classes created by Cocoa Dev Central are likely to be prefixed with " CDC ".

  • If you are subclassing the standard Cocoa class, it is recommended to combine the prefix with the superclass name, such as CDCTableView .

Variable names:

  • Variable names start with lowercase letters, but are internally capitalized wherever a new word appears:

     NSString * streetAddress  = @"1 Infinite Loop";
     NSString * cityName       = @"Cupertino";
     NSString * countyName     = @"Santa Clara";

--------- Correct way ---------

     NSString       * hostName;
     NSNumber       * ipAddress;
     NSArray        * accounts;


--------- Wrong way ---------

     NSString       * HST_NM;      // all caps and too terse
     NSNumber       * theip;       // a word or abbreviation?
     NSMutableArray * nsma;        // completely ambiguous


  1. Variables cannot start with a number, spaces, and special characters other than underscores.

  2. Apple is moving away from using the underscore as a prefix for a private instance variable.

     NSString * name    // correct!
     NSString * _name   // _incorrect_

Variable names: pointer type

  • In real-life terms, a variable name usually does not indicate a type unless it is something general, such as NSString, NSArray, NSNumber, or BOOL.


     NSString       * accountName;
     NSMutableArray * mailboxes;
     NSArray        * defaultHeaders;
     BOOL             userInputWasUpdated;


Ok but not perfect

     NSString       * accountNameString;
     NSMutableArray * mailboxArray;
     NSArray        * defaultHeadersArray;
     BOOL             userInputWasUpdatedBOOL;


  1. If the variable is not one of these types, the name should reflect it. Also, there are certain classes for which you only need one instance. In this case, just provide a variable based on the class name. The font manager is a good example of this.

When to specify the type

     NSImage             * previewPaneImage;  // self-explanatory
     NSProgressIndicator * uploadIndicator;   // shows progress for uploads
     NSFontManager       * fontManager;       // only one of these, basic name ok


Method names

  • Methods are perhaps the most important topic we can talk about. Most object oriented languages ​​use syntax.

  • While these method names are easy to write the first time around, the actual behavior is not clear. This is much more problematic among the sheer amount of surrounding code.

  • Cocoa programmers think backwards, choosing a method name based on how it will look in real use. Let's say I want to write a memory file written to disk.

In Cocoa / Objective-C, it looks like this:

    [fileWrapper writeToFile: path atomically: YES updateFilenames: YES];


Method names: Accessors

  • Unlike many other languages, Objective-C does not recommend using the "get" prefix for simple accessories. Instance variables and methods can have the same name, so use this to your advantage:


      - (NSString *) name;
      - (NSString *) color;

      name  = [object name];
      color = [object color];



      - (NSString *) getName;
      - (NSColor  *) getColor;

      name  = [object getName];
      color = [object getColor];


  1. The "get" prefix is ​​used, however, in situations where you return a value indirectly via a memory address:

When to use the "Get" prefix

// copy objects from NSArray to buffer

      id *buffer = (id *) malloc(sizeof(id) * [array count]);
      [array getObjects: buffer];
      ( Don't worry if you don't know what malloc does. )
      The "set" prefix is always used on setters, though:

      [object setName:  name];
      [object setColor: color];



  • Not all accessors return values ​​like name, date, height, etc. Some of them represent especially the quality of the object. They are often represented by BOOLs .

  • For example, "selectable". In Objective-C, the getter for this key is called -isSelectable, but setter -setSelectable:

        BOOL selectable = [textView isSelectable];
        BOOL editable   = [textView isEditable];
        [textView setSelectable: YES];    // no "is"
        [textView setEditable:   YES];    // no "is"
         // if textview is editable.
        if ([textView isEditable])
        [textView setEditable: NO];

  • Keep in mind that naming your accessories according to all of these rules is not purely a matter of clarity and aesthetics. Cocoa relies heavily on KVC for most of its magic, while KVC relies on the correctly named accessors.

I think this will help you.





All Articles