title: What is the meaning of nonatomic and retain in a property declaration
body: <p>i'm new to iOS programming. Can anyone tell me the exact meaning of the following line of code 
  <code>@property(**nonatomic, retain**) UIView *singleTapView;</code></p>
  
  <p>i have been using @property for many a times with out actually knowing the exact meaning of the <code>(nonatomic, retain or assign or copy)</code>function.. Can anyone help me with this.. 
  Thankyou</p>