title: Newbie question: NSOperation for iphone SDK
body: <p>Hi I got some problem with NSOperation .
  I always got error at <code>self = [super init];</code> (already use break point to find this)
  it always return &quot;Program received signal: EXC_BAD_ACCESS&quot; all the time</p>
  <pre><code>//AddThread.h
  @interface AddThread : NSOperation
  {
      NSString * str;
  }
  @property (nonatomic,retain) NSString * str;
  -(id) initWithString:(NSString *) tmpStr;
  @end
  </code></pre>
  <p>and for .m</p>
  <pre><code>//AddThread.m
  #import &quot;AddThread.h&quot;
  @implementation AddThread
  @synthesize str;
  - (id) initWithString:(NSString *)tmpStr
  {
      self = [super init];
      if (self != nil)
      {
          self.str = tmpStr;
      }
      //NSLog(self);
      //[super init];
          return self;
  }
  - (void) main
  {
      NSLog(self.str);
  }
  - (void) dealloc{
      [str release];
      str = nil;
      [super dealloc];
  }
  @end
  </code></pre>
  <p>well I stuck with this for while and if possible any resources ,articles things for basic example of NSoperation?</p>