title: Reason to use ivars vs properties in objective c
body: <p>I have been unable to find any information on this topic and most of what I know about it has come by complete accident (and a few hours of trying to figure out why my code wasn't working). While learning objective-c most tutorials I have found make variables and properties with the same name. I don't understand the significance because it seems that the property does all the work and the variable just kind of sits there. For instance: </p>
  
  <p><strong>Test.h</strong></p>
  
  <pre><code>@interface Test : NSObject {
      int _timesPlayed, _highscore;
  }
  
  @property int timesPlayed, highscore;
  
  // Methods and stuff
  
  @end
  </code></pre>
  
  <p><strong>Test.m</strong></p>
  
  <pre><code>@implementation Test
  
    @synthesize timesPlayed = _timesPlayed;
    @synthesize highscore   = _highscore;
  
    // methods and stuff
  
  @end
  </code></pre>
  
  <p><strong>What I know</strong></p>
  
  <p>1) Okay so today I found out (after hours of confusion) that no matter how much changing you do to the properties <code>highscore = 5091231</code> it won't change anything when you try to call [test highscore] as it will still be returning the value of _highscore which (I think) is the ivar that was set in test.h. So all changing of variables in test.m needs to be changing _highscore and not highscore. (Correct me if I'm wrong here please)</p>
  
  <p>2) If I understand it correctly (I probably don't) the ivars set in test.h represent the actual memory where as the @properties are just ways to access that memory. So outside of the implementation I can't access _highscore without going through the property.</p>
  
  <p><strong>What I don't understand</strong></p>
  
  <p>Basically what I don't get about this situation is whether or not I need to use the ivars at all or if I can just use @property and @synthesize. It seems like the ivars are just extra code that don't really do anything but confuse me. Some of the most recent tuts I've seen don't seem to use ivars but then some do. So is this just a coding preference thing or is it actually important? I have tried searching through Apple's Documentation but I get rather lost in there and never seem to find what I'm looking for. Any guidance will be greatly appreciated.</p>